CircleCI Status

Postmortem: ## Summary

Between October 1 and October 8, 2026, CircleCI customers experienced five separate incidents in which jobs waited longer than normal to start, or failed to start. Three of the incidents were driven by limited instance availability from our cloud provider. One was caused by a configuration issue in our scheduling infrastructure, and one by memory limits on an internal service, which we raised during the incident.

• October 1, 07:57 to 10:24 UTC: Docker Gen 2 jobs waited up to 30 minutes to start. A configuration issue prevented the Gen 2 scheduling servers from using their high-performance local disks. During a burst in traffic, the fallback disks saturated and job placement slowed.
• October 7, 13:27 to 14:06 UTC: Machine jobs waited longer than normal because we could not acquire enough virtual machines from our cloud provider.
• October 7, 14:24 to 15:21 UTC: Some jobs failed with an infrastructure error, and workflows were delayed. The service that gives each job its configuration at startup ran out of memory and restarted.
• October 7, 18:49 to 20:05 UTC: Docker Gen 2 jobs waited longer than normal because we could not acquire enough instances from our cloud provider.
• October 8, 12:48 to 16:00 UTC: Linux machine jobs and remote Docker jobs waited up to 50 minutes to start. Our cloud provider did not have enough of the instance type we request, and a defect in the logic that picks a different instance type kept us from using alternatives.

Jobs that waited during these incidents were delayed, not lost. Customers whose jobs failed with an infrastructure error during the October 7 incident from 14:24 to 15:21 UTC can rerun them.

The original status pages can be found below:

• October 1 - Delays starting Gen 2 Docker Jobs
• October 7 - Delay on starting Machine Job Tasks
• October 7 - Elevated level of infra fails on customer jobs
• October 7 - Increased task wait times for Docker Gen2
• October 8 - Elevated wait times for machine jobs

Background

Every job that runs on CircleCI needs compute. Where that compute comes from depends on the executor.

Docker jobs run on clusters of servers that schedule work onto a fleet of instances. The scheduler is the software on those servers that decides which instance runs each job. Gen 2 Docker jobs ran on one such cluster at the time of the October 1 incident. Gen 1 Docker jobs are spread across several clusters.

Machine jobs, including remote Docker jobs, get a dedicated virtual machine. A remote Docker job is handled as a Linux machine job from submission through provisioning. Our machine provisioning service requests each machine from our cloud provider in one of the two regions we normally use for machine jobs. When the provider cannot supply the instance type we request, the service falls back: it requests a different instance type, or a different region, from a list we maintain. A job waits until a machine is available.

When any job starts, it asks a job configuration service for its configuration. That service runs as a set of pods, which are small copies of the same program. If too many pods stop, the remaining pods carry more load, and jobs cannot start until the service recovers.

These paths depend on three kinds of capacity: the throughput of our scheduling systems, the supply of instances from our cloud provider, and the memory and number of copies of the services that start jobs. A shortfall in any of them makes jobs wait or fail.

What Happened

(All times UTC)

October 1: Docker Gen 2 jobs delayed up to 30 minutes

At 07:44, disk activity on the servers that schedule Gen 2 Docker jobs rose to 90% of capacity and stayed there. At 07:57, the number of Docker jobs waiting to start began to grow, and wait times rose with it. An automated alert paged the on-call engineer at 08:08. We declared an incident at 08:42.

At 08:43, engineers identified high disk latency on the scheduling servers. They first believed the disks were too slow for the load, so they prepared a change to a faster disk type. At 09:01, the team agreed on two workstreams: move the servers to faster disks, and add a second Gen 2 cluster so that jobs would split across two clusters.

At 09:41, engineers found the root cause. Each scheduling server has fast disks attached directly to it, and the scheduler is meant to keep its working data there. These servers run on a security-hardened operating system image, and on that image the fast disks were not being used. The scheduler wrote its data to slower network-attached disks instead. The script that sets up the fast disks failed without an error, and a gap in logging on these servers hid the failure. Gen 2 traffic had also become increasingly bursty. The slower disks saturated during those bursts, and the scheduler fell behind.

Wait times peaked at 09:54, when jobs on the Gen 2 medium resource class waited up to 30 minutes. At 09:55, engineers applied a fix that set up the fast disks correctly. At 10:11, the scheduler began placing jobs faster, which confirmed the servers could keep up with new jobs. Wait times for Gen 2 medium fell to 13 minutes at 10:14, 7 minutes at 10:17, and 1 minute 30 seconds at 10:20. We moved the status page to monitoring at 10:24 and resolved the incident at 10:45.

At 11:20, the second Gen 2 cluster began running jobs.

October 7, 13:27 to 14:06: Elevated wait times for machine jobs

We declared an incident at 13:27 after seeing elevated queueing and wait times. We posted to the status page at 13:31. At 13:31, engineers saw that we were struggling to acquire virtual machines for machine jobs, and that the number of jobs waiting to start was high mainly for machine jobs. At 13:34, wait times were elevated across executors.

At 13:48, wait times began to recover as more machines became available, and we resolved the incident at 14:06.

October 7, 14:24 to 15:21: Job failures and workflow delays

Shortly after the previous incident was marked as resolved, we declared a new incident at 14:24 due to a sharp drop in the number of jobs submitted to our execution systems. At 14:26, engineers saw that pods of the job configuration service were restarting. Pods that restart leave fewer copies of the service to answer requests, and jobs that could not retrieve their configuration after repeated attempts failed with an infrastructure error. Workflows that were already running waited for updates from jobs that had not started.

At 14:35, engineers increased the amount of available memory to the pods and increased the number of pods, which gave the service more copies to share the load. We also increased the amount of memory available Job submissions began recovering, and the number of messages flowing through our workflow system returned to normal levels. At 14:44, we moved the status page to monitoring.

Pods in the job configuration service reached their memory limits and restarted. We increased memory allocations and pod counts, and the service recovered. At 15:13, we increased the number of instances in our Gen 2 Docker clusters so we could work through the backlog of waiting jobs quickly. We resolved the incident at 15:21.

October 7, 18:49 to 20:05: Elevated wait times for Docker Gen 2 jobs

We declared a new incident at 18:49 after Docker Gen 2 wait times rose. At 18:51, engineers confirmed that a shortage of available instances kept us from acquiring enough of them, which raised wait times. Wait times differed by resource class size.

At 19:52, average wait times were lower than an hour earlier as more capacity became available, though brief spikes continued, and we moved the status page to monitoring. We resolved the incident at 20:05.

October 8: Linux machine and remote Docker jobs wait up to 50 minutes

We declared an incident at 12:48 after seeing a large number of jobs waiting to start and long wait times for machine and remote Docker jobs. At 12:49, engineers saw that our cloud provider could not supply enough instances. Delays continued to climb as we investigated.

At 13:13, we began examining the logic that chooses a different instance type or region when our first choice is unavailable. At 13:24, we suspected that a defect in that logic was stopping us from using other instance types in our primary region, so we disabled our fallback region and confirmed the cause of the defect. Engineers began working on a fix and deployed it at 14:49. The service began requesting other instance types and started machines in large numbers. At 14:58, the queue of jobs waiting for a machine dropped steadily. Average wait times across resource classes continued to drop over the next hour as we worked through the backlog of waiting jobs.

At 16:00, the queue of jobs waiting for a machine cleared and the number of waiting jobs returned to normal. We moved the status page to monitoring at 16:09 and resolved the incident at 16:35.

Future Prevention and Process Improvement

We are taking the following steps to strengthen the resilience of job start times, including supply diversification, fallback logic, and earlier detection.

We are expanding our compute regions. In the October 7 and October 8 incidents, our cloud provider could not supply enough instances in the regions we used. We are adding new regions to our fallback logic in order handle spikes for demand that outpace our preferred regions.

We are fixing the logic that picks a different instance type. On October 8, a defect kept the machine provisioning service from using other instance types in the same region. We deployed a fix during the incident and are now reviewing and refactoring this logic as a whole, with tests, so that a shortage of one instance type moves work to another.

We are expanding the instance types we offer and securing additional capacity. We are working with our cloud provider to reserve additional capacity in our existing regions, and we are adding instance types that jobs can run on. Industry demand for high-performance compute is growing. We are diversifying where and how we source capacity so our customers are insulated from supply variation.

We added a second Gen 2 Docker cluster so traffic bursts are distributed across two clusters. We are also adding alerts on scheduling server disk saturation and on how fast the scheduler places jobs, and an alert that fires when a server starts without its fast disks in use. We made the disk setup script fail with an error, and we restored log shipping from these servers so that a similar problem is visible sooner.

Customer experience is our top priority, and we commit to continually improving the reliability of our systems to match the trust that our customers place in us. We thank our customers for their patience while our team worked to resolve these incidents. Please reach out to our support team with any questions or concerns.

Resolved: Between 12:40 UTC and 16:00 UTC on October 8, customers using Linux machine jobs and remote Docker experienced elevated wait times. The issue has been resolved and wait times have returned to normal. We thank you for your patience while our team worked on implementing a fix.

Monitoring: Wait times for customers using Linux machine jobs and remote Docker have returned to normal. We are monitoring to confirm wait times remain stable while we continue to add capacity. We will provide another update by 16:30 UTC.

Identified: Wait times continue to decrease, but customers using Linux machine jobs and remote Docker are still experiencing delays. Wait times currently average about 90 seconds, with the longest waits up to about 6 minutes on some resource classes. We are working to add capacity as quickly as possible. We will provide another update by 16:30 UTC.

Identified: Wait times continue to decrease, but customers using Linux machine jobs and remote Docker are still experiencing delays. Wait times currently average about 6 minutes. The longest waits, up to about 20 minutes, are on the 2xlarge, arm.2xlarge and gpu.nvidia.small resource classes. We are working to add capacity as quickly as possible. We will provide another update by 16:00 UTC.

Identified: A fix has been deployed and wait times are decreasing, but customers using Linux machine jobs and Remote Docker are still experiencing delays. Wait times currently average about 11 minutes, with the longest waits exceeding 35 minutes on some resource classes. We are working to add capacity as quickly as possible. We will provide another update by 15:30 UTC.

Identified: Customers using Linux machine jobs and remote Docker are experiencing elevated wait times. Wait times have started to decrease and now average about 20 minutes, with the longest waits exceeding 40 minutes on some resource classes. Our engineers have identified the issue and are working on a fix. We will provide another update by 15:00 UTC.

Identified: Customers using Linux machine jobs are experiencing elevated wait times, averaging about 40 minutes, with the longest waits exceeding 50 minutes. Most Linux machine resource classes are affected, including medium, large, xlarge, 2xlarge and their Arm equivalents. Our engineers have identified the issue and are working on a fix. We will provide another update by 14:30 UTC.

Identified: Customers using Linux machine jobs are experiencing elevated wait times, averaging about 11 minutes, with the longest waits exceeding 30 minutes on the medium, arm.medium and arm.large resource classes. Our engineers have identified the issue and are working on a fix. We will provide another update by 14:00 UTC.

Identified: Customers may be experiencing elevated wait times for machine jobs. We are working to resolve this.

Resolved: Between approximately 14:00 UTC and 15:51 UTC on October 14, customers running macOS jobs that use Xcode 26.6.0 or Xcode 26.4 experienced delays starting jobs. From approximately 14:00 UTC, jobs that use Xcode 26.6.0 on the M4 Pro large resource class waited 30 minutes or more to start, and these delays recovered at approximately 15:12 UTC. From approximately 15:11 UTC, jobs that use Xcode 26.4 waited about 30 minutes to start.

The issue has been resolved and all affected functionality has returned to normal. We thank you for your patience while our team worked on implementing a fix.

Identified: Delays starting macOS jobs that use Xcode 26.6.0 have recovered. Since approximately 15:11 UTC, macOS jobs that use Xcode 26.4 are experiencing delays starting, with wait times of about 30 minutes.

Thank you for your patience while our engineers work to resolve this. We will provide another update by 15:45 UTC.

Investigating: Since approximately 14:00 UTC, customers running macOS jobs that use Xcode 26.6.0 on the M4 Pro large resource class are experiencing delays starting jobs. Wait times have reached 30 minutes or more.

Thank you for your patience while our engineers investigate. We will provide another update by 15:30 UTC.

Postmortem: ## Summary

Between 11:15 UTC and 23:47 UTC on October 9, CircleCI customers experienced hours-long delays and failures across pipelines, workflows and jobs, along with delays in the CircleCI UI, API and notifications.

• From 11:15 to 13:00 UTC, pipelines were created but not processed, and outbound webhooks and Slack and email notifications were not sent.
• From 13:00 to 14:40 UTC, workflows and jobs started with delays while we worked through the backlog.
• From 15:15 to 20:48 UTC, workflows and jobs started with increasing delays, of up to about an hour, and the CircleCI UI and API fell behind by up to about 2 hours. During this time, some jobs failed to start and some in-progress workflows failed.
• From 20:48 to 22:10 UTC, we temporarily paused starting new workflows and jobs so our systems could recover. New pipelines were accepted and queued during this time.
• From 22:10 to 23:47 UTC, queued workflows and jobs resumed and were successfully processed. Some of them had waited up to about 2 hours.
• By 23:47, the incident was mitigated.

The status page for this incident can be found at October 9 - Delay in data appearing in UI and API. Customers experienced a similar incident earlier in the week at October 6 - Delays in pipelines, workflows, UI data, and notifications.

Multiple CircleCI services use Temporal backed by Postgres as a reliable queueing mechanism, and both incidents had the same cause: the rate of writes to Temporal's Postgres instance were faster than Postgres’s transaction log could archive those writes. In both cases, this caused multi-hour delays in processing both pipelines and status notifications.

We evaluated several mitigations, then paused new workflow starts so the system could recover safely, and ramped back up gradually. We then throttled work back up until our systems returned to normal.

To permanently resolve the bottleneck, we have split work across multiple Temporal instances, each with its own independent database and worker clusters, and we load-balance across them. We had already scheduled infrastructure work starting the week of October 12 that would have removed this exact bottleneck and prevented these incidents. So starting 19:11 on October 9 our engineering team implemented, tested, and rolled out a simpler version of these changes within a few hours. We further added new alerting and tuned the underlying databases for better performance under high load.

Customers whose jobs failed during this window may rerun them.

Background

To run customer jobs, CircleCI executes a series of steps: we accept customer pipelines; we assign jobs for those pipelines to workers; we deliver status updates for those pipelines and jobs; and we charge customers for the credits those jobs consume. Each of these steps is implemented by an independent service, with reliable queues in between.

Historically we have implemented these reliable queues with RabbitMQ on top of durable storage, with exponential backoff and dead letter queues for reliability. Over the last year, we have increasingly reimplemented our reliable queues on Temporal, which provides far better durability and reliability guarantees over a simpler and more powerful programming model. Our build service (which turns a pipeline config into an executable plan), our workflow orchestrator service (which distributes tasks onto workers), our notification service (which delivers status updates), and our charging service (which charges customers for credits) all now use Temporal.

Temporal stores the state for its workflows and activities (called “history”) in a database, and this is the only component in a Temporal instance that is synchronous and stateful. As a consequence, a Temporal instance’s ability to accept and execute workflows is dependent on the write rate of its backing database. We have also configured Temporal to delete completed workflows and activities from its history 3 days after they complete.

At the time of this incident, we used a single clustered Temporal instance backed by a Multi-AZ Postgres RDS instance for all of these reliable queues. While a Multi-AZ RDS instance is resilient to zone failures, it maintains database consistency via a single write-ahead-log (WAL). At the time we had configured our Postgres instance to store its WAL on a Dedicated Log Volume (DLV) so log writes did not compete with data writes. The database archives the log continuously to backup storage, and it can only reuse space on the volume after the log has been archived. If the database writes logs faster than it archives, the volume fills and Postgres has no space to the write its WAL log. Then the database stops accepting incoming writes and goes entirely read-only. An RDS DLV is limited to 1TB of storage and 3000 IOPS and per AWS these limits are hardcoded and cannot be increased.

What Happened

(All times UTC)

One of the contributing factors to the October 6 incident was that we were processing a high rate of Temporal history deletions at the same time as incoming work, which in turn put pressure on the backing database. To resolve the October 6 incident, we changed cleanup settings on Temporal’s largest tables and moved the transaction log back to its dedicated volume. These changes eliminated the major source of transaction log writes, but did not consider the additional log writes from scheduled deletions. Because we have configured Temporal to delete completed workflows and activities from its history 3 days after they complete, the October 6 history was scheduled to be deleted on October 9.

Starting at 08:00 on October 9, Temporal began processing those scheduled deletions, and as a consequence free space on the Postgres DLV began dropping precipitously, from 0.8TB at 08:00 to 0.1TB by 10:10. Our monitoring alerted at 10:28 and we declared an incident at 10:31. While our infrastructure team was investigating, at 11:15 the DLV ran out of space and the Postgres instance went read-only. This stopped all Temporal processing in its tracks.

At 11:42, we restarted Postgres to move the WAL log from the DLV onto the data volume and use the spare disk space and IOPS there. This maneuver had mitigated the incident on October 6, and we knew it would take roughly 60 minutes.

While the database was restarting, we began implementing several load-shedding techniques upstream of Temporal:

• We began investigating whether we should shed incoming workloads altogether to keep the rest moving, but ultimately decided that this would provide no value.
• At 12:29, we flagged off credit charging updates, which represented 12% of Temporal activities. This left the Pipeline Usage page with stale charging data, until we would backfill it, but would not lose data or prevent pipelines from running.

At 12:59, the database was back up and began processing work that had queued since 11:15 and by 14:40, this backlog had cleared and jobs were starting on time. However, by 15:15, delays returned as database’s routing cleanup had fallen far behind on the tables Temporal uses to track queued and scheduled work. Those tables normally hold tens of thousands of deleted rows awaiting cleanup, but by late afternoon, they held tens of millions of rows. Every Temporal operation had to read past those rows, so the database spent much more processing time on each one and Temporal ran slower. This resulted in customers continuing to see hour-long delays in starting pipelines and in status updates.

For the next several hours we attempted various mitigations, including:

• Manipulating Temporal configuration values to reduce database pressure. This had minimal effect.
• Running manual vacuum jobs to clean up dead rows in Postgres. This ended up competing for CPU with queries themselves, and was ultimately counterproductive. We cancelled them at 17:45 to relieve the pressure on the database load.
• We began trying to move all of the notification usecases to a separate Temporal instance. This represented 18% of Temporal activities. We successfully finished moving notifications by 17:07.
• At 17:16, we successfully implemented an optimization in our representation of pipeline state, which reduced it by 5%. That in turn reduced the size of database writes and therefore data pressure on the Postgres WAL log.

None of these fully mitigated the issue.

By 20:48, we realized that Postgres was now thrashing on database CPU and was no longer bottlenecked on log writes. We further realized that our upstream systems were both submitting new work and also retrying work that had earlier been submitted and failed. Recognizing that we were in a classic retry storm, we paused all incoming and retry work and let it queue up, in order to allow the database to fully complete in-process work. We then slowly throttled up queued work from 22:07 to keep the database at a sustainable load.

This fully succeeded by 23:47 when all queued work had started, and we closed the incident at 02:08 on October 10.

Future Prevention and Process Improvement

Multiple Temporal Instances

In parallel with incident mitigation and resolution, starting at 19:11 on October 9, we also began standing up multiple sharded Temporal instances and implementing the ability to load-balance incoming work between them.

Each of the multiple Temporal instances maintains its own independent database and worker clusters, and so is isolated from the others. As a postmortem action item from the October 6 incident, we had already scheduled infrastructure work that would have removed the bottleneck of a single Temporal instance and Postgres database, starting October 12 and expecting to take 2 weeks. On October 9, we realized that this work simply could not wait, so our engineering team implemented, tested, and rolled out a simpler version of the planned changes within a few hours.

These changes completed successfully at 01:45 on October 10.

In addition, we are changing how we store and monitor transaction logs. Our Temporal database no longer uses the fixed-size log volume. We are adding alerts on how far log archiving falls behind and how fast the database writes logs, so we can act hours earlier than we did on October 9.

We are also revisiting the Temporal's deletion schedule. Temporal deletes finished work a few days after it runs, so a busy day returns as database load later in the week. We are changing when and how quickly those deletions run.

We are changing how our systems retry when Temporal is slow. On October 9, our systems retried failed work against Temporal and added to its load. As we committed after the October 6 incident, we are changing our systems to wait for Temporal to recover so work is not dropped.

Conclusion

Customer experience is our top priority, and we commit to continually improving the reliability of our systems to match the trust that our customers place in us. We thank our customers for their patience while our team worked to resolve these incidents.

Please reach out to our support team with any questions or concerns.

Resolved: Between 11:15 UTC and 23:47 UTC on October 9, customers experienced delays and failures across pipelines, workflows and jobs, along with delays in the CircleCI UI, API and notifications.

From 11:15 to about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and Slack and email notifications were not sent. From about 13:00 to 14:40 UTC, workflows and jobs started with delays while we worked through the backlog.

From about 15:15 to 20:48 UTC, workflows and jobs started with increasing delays, of up to about an hour, and the CircleCI UI and API fell behind by up to about 2 hours. During this time, some jobs failed to start and some in-progress workflows failed.

From 20:48 to about 22:10 UTC, we temporarily paused starting new workflows and jobs so our systems could recover. New pipelines were accepted and queued during this time. From about 22:10 to 23:47 UTC, queued workflows and jobs resumed and were processed. Some of them had waited up to about 2 hours.

The issue has been resolved and all affected functionality has returned to normal. Usage charge data on the Project Usage page is not yet up to date and will be updated once our data backfills complete. Customers whose jobs failed during this window may rerun affected jobs. We thank you for your patience while our engineers worked on implementing a fix.

Monitoring: Workflows and jobs are starting and running normally, and the CircleCI UI and API are up to date. We are continuing to monitor our systems closely to make sure they remain stable.

We will provide another update by 02:00 UTC.

Identified: Workflows and jobs have continued to start normally, within seconds, and the CircleCI UI and API remain up to date. Slack and email notifications delayed earlier in the incident are still being delivered.

Usage charge data on the Project Usage page is stale.

We are continuing to monitor our systems closely and will provide another update by 01:15 UTC.

Identified: Since our last update, the backlog of queued workflows and jobs has cleared, as of about 23:47 UTC. Workflows and jobs are now starting within seconds, and the CircleCI UI and API are up to date. We are monitoring our systems closely to make sure they remain stable. We will provide another update by 00:30 UTC.

Identified: We are still working through a significant backlog of queued workflows and jobs. Wait times are improving but they remain longer than normal and some jobs have waited over an hour. The CircleCI UI and API remain up to date. Please avoid retriggering pipelines or workflows while the backlog clears, as this may create duplicates. We will provide another update by 00:00 UTC.

Identified: A large number of queued workflows and jobs have started, and the CircleCI UI and API have caught up and are showing updates normally with few delays. We are continuing to work through the remaining queued work. Jobs from the queue may have waited about an hour or more to start, and some Linux jobs are waiting up to about 10 minutes for capacity.

Please continue to avoid retriggering while queued work continues to process.

We will provide another update by 23:30 UTC.

Identified: Since our last update, we have begun gradually resuming work, and some queued workflows and jobs are starting again. Most queued work is still waiting, and jobs that do start may have waited over an hour. We are increasing the rate carefully to avoid overloading our systems. Delayed updates continue to appear in the CircleCI UI and API.

Please continue to avoid retriggering pipelines or workflows, as this may create duplicates as queued work resumes.

We will provide another update by 23:00 UTC.

Identified: Since our last update, most of the pipelines that were delayed earlier in the incident have now been processed, and their workflows are queued to start. New workflows and jobs remain paused while we prepare to resume work safely. Delayed updates continue to appear in the CircleCI UI and API.

Please continue to avoid retriggering pipelines or workflows, as this may create duplicates once work resumes.

We will provide another update by 22:30 UTC.

Identified: Since about 20:48 UTC, new workflows and jobs are not starting. We have temporarily paused starting new work so that our systems can catch up on work already in progress, including delayed updates to the CircleCI UI and API. Older updates are now appearing in the UI and API as this backlog clears. New pipelines are still being accepted and queued

Please avoid retriggering pipelines or workflows during this time, as this may create duplicates once work resumes.

We will provide another update by 22:00 UTC.

Identified: Jobs are starting faster and fewer are failing: most jobs are now starting within about 4 minutes, down from about 6 minutes, and the longest waits have dropped from about 30 minutes to about 20 minutes.

Pipelines from earlier in the incident are now being worked through.

The CircleCI UI is still behind, and some older updates may take longer to appear. Jobs may already have run even if the UI does not show them yet, so please avoid retriggering workflows that don't appear in the UI.

We will provide another update by 20:30 UTC.

Identified: Since our last update, jobs are starting faster: most are now starting within about 6 minutes, down from about 8 minutes. The CircleCI UI is catching up but still about an hour behind. New pipelines are being processed as they arrive.

Jobs may already have run even if the UI does not show them yet, so please avoid retriggering workflows that don't appear in the UI.

We will provide another update by 20:00 UTC.

Identified: What's changed since our last update

• Jobs are starting faster. Most are now starting within about 8 minutes, down from about 15 minutes, and the longest waits have dropped from over an hour to about 45 minutes.
• The CircleCI UI is beginning to catch up, but it is still behind. Workflows and jobs may already have run, or may be running, even if the UI shows them as not started or does not show them at all.
• Pipelines are being processed faster, but new pipelines are still delayed.

Still ongoing

• Some workflows and jobs are still failing.
• Please avoid retriggering workflows that don't yet appear in the UI, as this may create duplicates.
• Usage charge data on the Project Usage page is stale.

Next update We will provide another update by 19:30 UTC.

Identified: What's changed since our last update

• The CircleCI UI is about an hour behind, and up to about 90 minutes for some updates. Workflows and jobs may already have run, or may be running, even if the UI shows them as not started or does not show them at all.
• Jobs that are running are starting faster. Most are now starting within about 15 minutes, down from about 28 minutes, though some are still waiting over an hour.
• New pipelines are increasingly delayed.
• Some workflows are still failing. Workflows that could not be processed in time are being marked as failed.
• Please avoid retriggering workflows that don't yet appear in the UI, as this may create duplicates.

Still ongoing: Usage charge data on the Project Usage page is stale.

Next update We will provide another update by 19:00 UTC.

Identified: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent. Between about 13:00 UTC and 14:40 UTC, workflows and jobs started with delays while we worked through the backlog. Since about 15:15 UTC, workflows and jobs have again been starting with delays.

What’s impacted Customers triggering pipelines and running workflows and jobs, customers viewing pipelines, workflows and jobs in the CircleCI UI, and customers viewing usage data on the Project Usage page.

What to expect

• Since about 17:00 UTC, we are seeing an increase in delays. Most jobs are now taking about 25 minutes to start, and some are waiting up to about an hour.
• Since about 17:15 UTC, some in-progress workflows have failed and a small number of jobs are failing to start.
• New pipelines are being queued and are taking longer to start.
• The CircleCI UI is more than an hour behind. New workflows and status changes may take that long to appear.
• Please avoid retriggering workflows that don't yet appear in the UI, as this may create duplicates.
• Usage charge data on the Project Usage page is currently stale.

Our engineers continue to work to resolve the issue at hand.

Next update We will provide another update by 18:30 UTC.

Identified: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent. Between about 13:00 UTC and 14:40 UTC, workflows and jobs started with delays while we worked through the backlog. Since about 15:15 UTC, workflows and jobs have again been starting with delays.

What’s impacted Customers triggering pipelines and running workflows and jobs, customers viewing pipelines, workflows and jobs in the CircleCI UI, and customers viewing usage data on the Project Usage page.

What can you expect

• Since about 17:00 UTC, delays have increased significantly. Most jobs are now taking about 12 minutes to start, and some are waiting up to about 30 minutes.
• Since about 17:15 UTC, some jobs are failing to start.
• Pipelines are being processed more slowly, so some may take longer to start.
• The CircleCI UI is more than an hour behind. New workflows and status changes may take that long to appear.
• Please avoid retriggering workflows that don’t yet appear in the UI, as this may create duplicates.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers work to resolve this.

Next update We will provide another update by 18:00 UTC.

Monitoring: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent. Between about 13:00 UTC and 14:40 UTC, workflows and jobs started with delays while we worked through the backlog. Since about 15:15 UTC, workflows and jobs have again been starting with delays.

What’s impacted Customers running workflows and jobs, customers viewing pipelines, workflows and jobs in the CircleCI UI, and customers viewing usage data on the Project Usage page.

What can you expect

• Delays starting workflows and jobs are holding steady. Most jobs are starting within about 4 minutes, and some are waiting up to about 8 minutes, down from about 25 minutes.
• The CircleCI UI remains about 20 minutes behind on average, and some updates are taking longer. New workflows and status changes may take that long to appear.
• Please avoid retriggering workflows that don’t yet appear in the UI, as this may create duplicates.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers work to reduce these delays.

Next update We will provide another update by 17:30 UTC.

Monitoring: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent. Between about 13:00 UTC and 14:40 UTC, workflows and jobs started with delays while we worked through the backlog. Since about 15:15 UTC, workflows and jobs have again been starting with delays.

What's impacted Customers running workflows and jobs, customers viewing pipelines, workflows and jobs in the CircleCI UI, and customers viewing usage data on the Project Usage page.

What can you expect

• Delays starting workflows and jobs have stopped increasing and are beginning to ease. Most jobs are starting within about 4 minutes, and some are waiting up to about 25 minutes.
• The CircleCI UI is now about 20 minutes behind, down from about 30 minutes. New workflows and status changes may take that long to appear.
• Please avoid retriggering workflows that don't yet appear in the UI, as this may create duplicates.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers work to reduce these delays.

Next update We will provide another update by 17:00 UTC.

Monitoring: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent. Between about 13:00 UTC and 14:40 UTC, workflows and jobs started with delays while we worked through the backlog.

What's impacted Customers running workflows and jobs, customers viewing pipelines, workflows and jobs in the CircleCI UI, and customers viewing usage data on the Project Usage page.

What can you expect

• Since about 15:15 UTC, workflows and jobs have been starting with increasing delays. Most jobs are currently starting within about 4 minutes, and some are waiting up to about 20 minutes.
• The CircleCI UI remains about 30 minutes behind on average, and some updates are taking longer. New workflows and status changes may take that long to appear.
• Please avoid retriggering workflows that don't yet appear in the UI, as this may create duplicates.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers work to reduce these delays.

Next update We will provide another update by 16:30 UTC.

Monitoring: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent. Between about 13:00 UTC and 14:40 UTC, workflows and jobs started with delays while we worked through the backlog.

What's impacted Customers viewing pipelines, workflows and jobs in the CircleCI UI, and customers viewing usage data on the Project Usage page.

What can you expect

• Workflows and jobs are running on time.
• The CircleCI UI is about 30 minutes behind. New workflows and status changes may take that long to appear.
• Our engineers are actively working to speed up processing so the UI can catch up.
• Please avoid retriggering workflows that don't yet appear in the UI, as this may create duplicates.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers work to reduce this delay.

Next update We will provide another update by 16:00 UTC.

Monitoring: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent. Between about 13:00 UTC and 14:40 UTC, workflows and jobs started with delays while we worked through the backlog.

What’s impacted Customers running workflows and jobs, and customers viewing usage data on the Project Usage page.

What can you expect

• The backlog of pipelines and workflows from the incident has cleared.
• Since about 14:45 UTC, most workflows and jobs are starting within about 15 seconds, and start times are continuing to return to normal.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers monitor the recovery.

Next update We will provide another update by 15:20 UTC.

Identified: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent. Between about 13:00 UTC and 14:40 UTC, workflows and jobs started with delays while we worked through the backlog.

What’s impacted Customers running workflows and jobs, and customers viewing usage data on the Project Usage page.

What can you expect

• The backlog of workflows from pipelines triggered during the incident cleared at about 14:40 UTC.
• Most jobs are now starting within about 30 seconds, and some are waiting up to about 3 minutes.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers continue to work on the underlying issue.

Next update We will provide another update by 15:10 UTC.

Identified: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent.

What's impacted Customers running workflows and jobs, and customers viewing usage data on the Project Usage page.

What can you expect

• Delays starting workflows and jobs are improving. Most jobs are now starting within about 3 minutes, down from about 10 minutes at 13:50 UTC.
• Some workflows from pipelines triggered during the incident are still waiting up to about 40 minutes to start.
• Working through the backlog is taking slightly longer than expected. We now expect to clear it by about 14:45 UTC.
• Workflows from pipelines triggered during the incident are still waiting to start, so retriggering may result in duplicate workflows.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers work to resolve this.

Next update We will provide another update by 15:00 UTC.

Identified: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent.

What's impacted Customers running workflows and jobs, and customers viewing usage data on the Project Usage page.

What can you expect

• Pipelines are being processed again, including those triggered during the incident.
• Since about 13:25 UTC, workflows and jobs have been starting with increasing delays as we work through the backlog. Most jobs are currently starting within about 10 minutes, and some are waiting up to about 25 minutes.
• We expect to work through this backlog by about 14:35 UTC.
• Workflows from pipelines triggered during the incident are still waiting to start, so retriggering may result in duplicate workflows.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers work to resolve this.

Next update We will provide another update by 14:30 UTC.

Identified: Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent.

What's impacted: Customers triggering pipelines, and customers relying on outbound webhooks and email and Slack notifications.

What can you expect:

• Since about 13:00 UTC, pipelines are being processed again and jobs are starting.
• Most jobs are currently starting within about 4 minutes, and some are waiting up to about 10 minutes. Pipelines triggered during the incident are still being processed and may take longer to start.
• Outbound webhooks and notifications have resumed.
• Pipelines are still being processed from the backlog, so retriggering may result in duplicate pipelines.

Thank you for your patience while our engineers work to resolve this.

Next update: We will provide another update by 14:00 UTC.

Identified: What's impacted: Customers triggering pipelines, and customers relying on outbound webhooks and email and Slack notifications.

What can you expect Since 11:15 UTC:

• Pipelines are still being created while this is ongoing but not yet processed, so retriggering may result in duplicate pipelines.
• Outbound webhooks and transactional notifications (Slack and email) are not being sent.
• Pipeline statuses may not be visible.
• Usage charge data on the Project Usage page will be stale.

Thank you for your patience while our engineers work to resolve this.

Next update: We will provide another update by 13:30 UTC.

Identified: There is a delay in our data infrastructure causing delays before build data and some notifications become visible. We are working on a mitigation.

Postmortem: ## Summary

Between 11:15 UTC and 23:47 UTC on October 9, CircleCI customers experienced hours-long delays and failures across pipelines, workflows and jobs, along with delays in the CircleCI UI, API and notifications.

• From 11:15 to 13:00 UTC, pipelines were created but not processed, and outbound webhooks and Slack and email notifications were not sent.
• From 13:00 to 14:40 UTC, workflows and jobs started with delays while we worked through the backlog.
• From 15:15 to 20:48 UTC, workflows and jobs started with increasing delays, of up to about an hour, and the CircleCI UI and API fell behind by up to about 2 hours. During this time, some jobs failed to start and some in-progress workflows failed.
• From 20:48 to 22:10 UTC, we temporarily paused starting new workflows and jobs so our systems could recover. New pipelines were accepted and queued during this time.
• From 22:10 to 23:47 UTC, queued workflows and jobs resumed and were successfully processed. Some of them had waited up to about 2 hours.
• By 23:47, the incident was mitigated.

The status page for this incident can be found at October 9 - Delay in data appearing in UI and API. Customers experienced a similar incident earlier in the week at October 6 - Delays in pipelines, workflows, UI data, and notifications.

Multiple CircleCI services use Temporal backed by Postgres as a reliable queueing mechanism, and both incidents had the same cause: the rate of writes to Temporal's Postgres instance were faster than Postgres’s transaction log could archive those writes. In both cases, this caused multi-hour delays in processing both pipelines and status notifications.

We evaluated several mitigations, then paused new workflow starts so the system could recover safely, and ramped back up gradually. We then throttled work back up until our systems returned to normal.

To permanently resolve the bottleneck, we have split work across multiple Temporal instances, each with its own independent database and worker clusters, and we load-balance across them. We had already scheduled infrastructure work starting the week of October 12 that would have removed this exact bottleneck and prevented these incidents. So starting 19:11 on October 9 our engineering team implemented, tested, and rolled out a simpler version of these changes within a few hours. We further added new alerting and tuned the underlying databases for better performance under high load.

Customers whose jobs failed during this window may rerun them.

Background

To run customer jobs, CircleCI executes a series of steps: we accept customer pipelines; we assign jobs for those pipelines to workers; we deliver status updates for those pipelines and jobs; and we charge customers for the credits those jobs consume. Each of these steps is implemented by an independent service, with reliable queues in between.

Historically we have implemented these reliable queues with RabbitMQ on top of durable storage, with exponential backoff and dead letter queues for reliability. Over the last year, we have increasingly reimplemented our reliable queues on Temporal, which provides far better durability and reliability guarantees over a simpler and more powerful programming model. Our build service (which turns a pipeline config into an executable plan), our workflow orchestrator service (which distributes tasks onto workers), our notification service (which delivers status updates), and our charging service (which charges customers for credits) all now use Temporal.

Temporal stores the state for its workflows and activities (called “history”) in a database, and this is the only component in a Temporal instance that is synchronous and stateful. As a consequence, a Temporal instance’s ability to accept and execute workflows is dependent on the write rate of its backing database. We have also configured Temporal to delete completed workflows and activities from its history 3 days after they complete.

At the time of this incident, we used a single clustered Temporal instance backed by a Multi-AZ Postgres RDS instance for all of these reliable queues. While a Multi-AZ RDS instance is resilient to zone failures, it maintains database consistency via a single write-ahead-log (WAL). At the time we had configured our Postgres instance to store its WAL on a Dedicated Log Volume (DLV) so log writes did not compete with data writes. The database archives the log continuously to backup storage, and it can only reuse space on the volume after the log has been archived. If the database writes logs faster than it archives, the volume fills and Postgres has no space to the write its WAL log. Then the database stops accepting incoming writes and goes entirely read-only. An RDS DLV is limited to 1TB of storage and 3000 IOPS and per AWS these limits are hardcoded and cannot be increased.

What Happened

(All times UTC)

One of the contributing factors to the October 6 incident was that we were processing a high rate of Temporal history deletions at the same time as incoming work, which in turn put pressure on the backing database. To resolve the October 6 incident, we changed cleanup settings on Temporal’s largest tables and moved the transaction log back to its dedicated volume. These changes eliminated the major source of transaction log writes, but did not consider the additional log writes from scheduled deletions. Because we have configured Temporal to delete completed workflows and activities from its history 3 days after they complete, the October 6 history was scheduled to be deleted on October 9.

Starting at 08:00 on October 9, Temporal began processing those scheduled deletions, and as a consequence free space on the Postgres DLV began dropping precipitously, from 0.8TB at 08:00 to 0.1TB by 10:10. Our monitoring alerted at 10:28 and we declared an incident at 10:31. While our infrastructure team was investigating, at 11:15 the DLV ran out of space and the Postgres instance went read-only. This stopped all Temporal processing in its tracks.

At 11:42, we restarted Postgres to move the WAL log from the DLV onto the data volume and use the spare disk space and IOPS there. This maneuver had mitigated the incident on October 6, and we knew it would take roughly 60 minutes.

While the database was restarting, we began implementing several load-shedding techniques upstream of Temporal:

• We began investigating whether we should shed incoming workloads altogether to keep the rest moving, but ultimately decided that this would provide no value.
• At 12:29, we flagged off credit charging updates, which represented 12% of Temporal activities. This left the Pipeline Usage page with stale charging data, until we would backfill it, but would not lose data or prevent pipelines from running.

At 12:59, the database was back up and began processing work that had queued since 11:15 and by 14:40, this backlog had cleared and jobs were starting on time. However, by 15:15, delays returned as database’s routing cleanup had fallen far behind on the tables Temporal uses to track queued and scheduled work. Those tables normally hold tens of thousands of deleted rows awaiting cleanup, but by late afternoon, they held tens of millions of rows. Every Temporal operation had to read past those rows, so the database spent much more processing time on each one and Temporal ran slower. This resulted in customers continuing to see hour-long delays in starting pipelines and in status updates.

For the next several hours we attempted various mitigations, including:

• Manipulating Temporal configuration values to reduce database pressure. This had minimal effect.
• Running manual vacuum jobs to clean up dead rows in Postgres. This ended up competing for CPU with queries themselves, and was ultimately counterproductive. We cancelled them at 17:45 to relieve the pressure on the database load.
• We began trying to move all of the notification usecases to a separate Temporal instance. This represented 18% of Temporal activities. We successfully finished moving notifications by 17:07.
• At 17:16, we successfully implemented an optimization in our representation of pipeline state, which reduced it by 5%. That in turn reduced the size of database writes and therefore data pressure on the Postgres WAL log.

None of these fully mitigated the issue.

By 20:48, we realized that Postgres was now thrashing on database CPU and was no longer bottlenecked on log writes. We further realized that our upstream systems were both submitting new work and also retrying work that had earlier been submitted and failed. Recognizing that we were in a classic retry storm, we paused all incoming and retry work and let it queue up, in order to allow the database to fully complete in-process work. We then slowly throttled up queued work from 22:07 to keep the database at a sustainable load.

This fully succeeded by 23:47 when all queued work had started, and we closed the incident at 02:08 on October 10.

Future Prevention and Process Improvement

Multiple Temporal Instances

In parallel with incident mitigation and resolution, starting at 19:11 on October 9, we also began standing up multiple sharded Temporal instances and implementing the ability to load-balance incoming work between them.

Each of the multiple Temporal instances maintains its own independent database and worker clusters, and so is isolated from the others. As a postmortem action item from the October 6 incident, we had already scheduled infrastructure work that would have removed the bottleneck of a single Temporal instance and Postgres database, starting October 12 and expecting to take 2 weeks. On October 9, we realized that this work simply could not wait, so our engineering team implemented, tested, and rolled out a simpler version of the planned changes within a few hours.

These changes completed successfully at 01:45 on October 10.

In addition, we are changing how we store and monitor transaction logs. Our Temporal database no longer uses the fixed-size log volume. We are adding alerts on how far log archiving falls behind and how fast the database writes logs, so we can act hours earlier than we did on October 9.

We are also revisiting the Temporal's deletion schedule. Temporal deletes finished work a few days after it runs, so a busy day returns as database load later in the week. We are changing when and how quickly those deletions run.

We are changing how our systems retry when Temporal is slow. On October 9, our systems retried failed work against Temporal and added to its load. As we committed after the October 6 incident, we are changing our systems to wait for Temporal to recover so work is not dropped.

Conclusion

Customer experience is our top priority, and we commit to continually improving the reliability of our systems to match the trust that our customers place in us. We thank our customers for their patience while our team worked to resolve these incidents.

Please reach out to our support team with any questions or concerns.

Resolved: Between 11:15 UTC and 23:47 UTC on October 9, customers experienced delays and failures across pipelines, workflows and jobs, along with delays in the CircleCI UI, API and notifications.

From 11:15 to about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and Slack and email notifications were not sent. From about 13:00 to 14:40 UTC, workflows and jobs started with delays while we worked through the backlog.

From about 15:15 to 20:48 UTC, workflows and jobs started with increasing delays, of up to about an hour, and the CircleCI UI and API fell behind by up to about 2 hours. During this time, some jobs failed to start and some in-progress workflows failed.

From 20:48 to about 22:10 UTC, we temporarily paused starting new workflows and jobs so our systems could recover. New pipelines were accepted and queued during this time. From about 22:10 to 23:47 UTC, queued workflows and jobs resumed and were processed. Some of them had waited up to about 2 hours.

The issue has been resolved and all affected functionality has returned to normal. Usage charge data on the Project Usage page is not yet up to date and will be updated once our data backfills complete. Customers whose jobs failed during this window may rerun affected jobs. We thank you for your patience while our engineers worked on implementing a fix.

Monitoring: Workflows and jobs are starting and running normally, and the CircleCI UI and API are up to date. We are continuing to monitor our systems closely to make sure they remain stable.

We will provide another update by 02:00 UTC.

Identified: Workflows and jobs have continued to start normally, within seconds, and the CircleCI UI and API remain up to date. Slack and email notifications delayed earlier in the incident are still being delivered.

Usage charge data on the Project Usage page is stale.

We are continuing to monitor our systems closely and will provide another update by 01:15 UTC.

Identified: Since our last update, the backlog of queued workflows and jobs has cleared, as of about 23:47 UTC. Workflows and jobs are now starting within seconds, and the CircleCI UI and API are up to date. We are monitoring our systems closely to make sure they remain stable. We will provide another update by 00:30 UTC.

Identified: We are still working through a significant backlog of queued workflows and jobs. Wait times are improving but they remain longer than normal and some jobs have waited over an hour. The CircleCI UI and API remain up to date. Please avoid retriggering pipelines or workflows while the backlog clears, as this may create duplicates. We will provide another update by 00:00 UTC.

Identified: A large number of queued workflows and jobs have started, and the CircleCI UI and API have caught up and are showing updates normally with few delays. We are continuing to work through the remaining queued work. Jobs from the queue may have waited about an hour or more to start, and some Linux jobs are waiting up to about 10 minutes for capacity.

Please continue to avoid retriggering while queued work continues to process.

We will provide another update by 23:30 UTC.

Identified: Since our last update, we have begun gradually resuming work, and some queued workflows and jobs are starting again. Most queued work is still waiting, and jobs that do start may have waited over an hour. We are increasing the rate carefully to avoid overloading our systems. Delayed updates continue to appear in the CircleCI UI and API.

Please continue to avoid retriggering pipelines or workflows, as this may create duplicates as queued work resumes.

We will provide another update by 23:00 UTC.

Identified: Since our last update, most of the pipelines that were delayed earlier in the incident have now been processed, and their workflows are queued to start. New workflows and jobs remain paused while we prepare to resume work safely. Delayed updates continue to appear in the CircleCI UI and API.

Please continue to avoid retriggering pipelines or workflows, as this may create duplicates once work resumes.

We will provide another update by 22:30 UTC.

Identified: Since about 20:48 UTC, new workflows and jobs are not starting. We have temporarily paused starting new work so that our systems can catch up on work already in progress, including delayed updates to the CircleCI UI and API. Older updates are now appearing in the UI and API as this backlog clears. New pipelines are still being accepted and queued

Please avoid retriggering pipelines or workflows during this time, as this may create duplicates once work resumes.

We will provide another update by 22:00 UTC.

Identified: Jobs are starting faster and fewer are failing: most jobs are now starting within about 4 minutes, down from about 6 minutes, and the longest waits have dropped from about 30 minutes to about 20 minutes.

Pipelines from earlier in the incident are now being worked through.

The CircleCI UI is still behind, and some older updates may take longer to appear. Jobs may already have run even if the UI does not show them yet, so please avoid retriggering workflows that don't appear in the UI.

We will provide another update by 20:30 UTC.

Identified: Since our last update, jobs are starting faster: most are now starting within about 6 minutes, down from about 8 minutes. The CircleCI UI is catching up but still about an hour behind. New pipelines are being processed as they arrive.

Jobs may already have run even if the UI does not show them yet, so please avoid retriggering workflows that don't appear in the UI.

We will provide another update by 20:00 UTC.

Identified: What's changed since our last update

• Jobs are starting faster. Most are now starting within about 8 minutes, down from about 15 minutes, and the longest waits have dropped from over an hour to about 45 minutes.
• The CircleCI UI is beginning to catch up, but it is still behind. Workflows and jobs may already have run, or may be running, even if the UI shows them as not started or does not show them at all.
• Pipelines are being processed faster, but new pipelines are still delayed.

Still ongoing

• Some workflows and jobs are still failing.
• Please avoid retriggering workflows that don't yet appear in the UI, as this may create duplicates.
• Usage charge data on the Project Usage page is stale.

Next update We will provide another update by 19:30 UTC.

Identified: What's changed since our last update

• The CircleCI UI is about an hour behind, and up to about 90 minutes for some updates. Workflows and jobs may already have run, or may be running, even if the UI shows them as not started or does not show them at all.
• Jobs that are running are starting faster. Most are now starting within about 15 minutes, down from about 28 minutes, though some are still waiting over an hour.
• New pipelines are increasingly delayed.
• Some workflows are still failing. Workflows that could not be processed in time are being marked as failed.
• Please avoid retriggering workflows that don't yet appear in the UI, as this may create duplicates.

Still ongoing: Usage charge data on the Project Usage page is stale.

Next update We will provide another update by 19:00 UTC.

Identified: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent. Between about 13:00 UTC and 14:40 UTC, workflows and jobs started with delays while we worked through the backlog. Since about 15:15 UTC, workflows and jobs have again been starting with delays.

What’s impacted Customers triggering pipelines and running workflows and jobs, customers viewing pipelines, workflows and jobs in the CircleCI UI, and customers viewing usage data on the Project Usage page.

What to expect

• Since about 17:00 UTC, we are seeing an increase in delays. Most jobs are now taking about 25 minutes to start, and some are waiting up to about an hour.
• Since about 17:15 UTC, some in-progress workflows have failed and a small number of jobs are failing to start.
• New pipelines are being queued and are taking longer to start.
• The CircleCI UI is more than an hour behind. New workflows and status changes may take that long to appear.
• Please avoid retriggering workflows that don't yet appear in the UI, as this may create duplicates.
• Usage charge data on the Project Usage page is currently stale.

Our engineers continue to work to resolve the issue at hand.

Next update We will provide another update by 18:30 UTC.

Identified: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent. Between about 13:00 UTC and 14:40 UTC, workflows and jobs started with delays while we worked through the backlog. Since about 15:15 UTC, workflows and jobs have again been starting with delays.

What’s impacted Customers triggering pipelines and running workflows and jobs, customers viewing pipelines, workflows and jobs in the CircleCI UI, and customers viewing usage data on the Project Usage page.

What can you expect

• Since about 17:00 UTC, delays have increased significantly. Most jobs are now taking about 12 minutes to start, and some are waiting up to about 30 minutes.
• Since about 17:15 UTC, some jobs are failing to start.
• Pipelines are being processed more slowly, so some may take longer to start.
• The CircleCI UI is more than an hour behind. New workflows and status changes may take that long to appear.
• Please avoid retriggering workflows that don’t yet appear in the UI, as this may create duplicates.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers work to resolve this.

Next update We will provide another update by 18:00 UTC.

Monitoring: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent. Between about 13:00 UTC and 14:40 UTC, workflows and jobs started with delays while we worked through the backlog. Since about 15:15 UTC, workflows and jobs have again been starting with delays.

What’s impacted Customers running workflows and jobs, customers viewing pipelines, workflows and jobs in the CircleCI UI, and customers viewing usage data on the Project Usage page.

What can you expect

• Delays starting workflows and jobs are holding steady. Most jobs are starting within about 4 minutes, and some are waiting up to about 8 minutes, down from about 25 minutes.
• The CircleCI UI remains about 20 minutes behind on average, and some updates are taking longer. New workflows and status changes may take that long to appear.
• Please avoid retriggering workflows that don’t yet appear in the UI, as this may create duplicates.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers work to reduce these delays.

Next update We will provide another update by 17:30 UTC.

Monitoring: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent. Between about 13:00 UTC and 14:40 UTC, workflows and jobs started with delays while we worked through the backlog. Since about 15:15 UTC, workflows and jobs have again been starting with delays.

What's impacted Customers running workflows and jobs, customers viewing pipelines, workflows and jobs in the CircleCI UI, and customers viewing usage data on the Project Usage page.

What can you expect

• Delays starting workflows and jobs have stopped increasing and are beginning to ease. Most jobs are starting within about 4 minutes, and some are waiting up to about 25 minutes.
• The CircleCI UI is now about 20 minutes behind, down from about 30 minutes. New workflows and status changes may take that long to appear.
• Please avoid retriggering workflows that don't yet appear in the UI, as this may create duplicates.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers work to reduce these delays.

Next update We will provide another update by 17:00 UTC.

Monitoring: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent. Between about 13:00 UTC and 14:40 UTC, workflows and jobs started with delays while we worked through the backlog.

What's impacted Customers running workflows and jobs, customers viewing pipelines, workflows and jobs in the CircleCI UI, and customers viewing usage data on the Project Usage page.

What can you expect

• Since about 15:15 UTC, workflows and jobs have been starting with increasing delays. Most jobs are currently starting within about 4 minutes, and some are waiting up to about 20 minutes.
• The CircleCI UI remains about 30 minutes behind on average, and some updates are taking longer. New workflows and status changes may take that long to appear.
• Please avoid retriggering workflows that don't yet appear in the UI, as this may create duplicates.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers work to reduce these delays.

Next update We will provide another update by 16:30 UTC.

Monitoring: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent. Between about 13:00 UTC and 14:40 UTC, workflows and jobs started with delays while we worked through the backlog.

What's impacted Customers viewing pipelines, workflows and jobs in the CircleCI UI, and customers viewing usage data on the Project Usage page.

What can you expect

• Workflows and jobs are running on time.
• The CircleCI UI is about 30 minutes behind. New workflows and status changes may take that long to appear.
• Our engineers are actively working to speed up processing so the UI can catch up.
• Please avoid retriggering workflows that don't yet appear in the UI, as this may create duplicates.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers work to reduce this delay.

Next update We will provide another update by 16:00 UTC.

Monitoring: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent. Between about 13:00 UTC and 14:40 UTC, workflows and jobs started with delays while we worked through the backlog.

What’s impacted Customers running workflows and jobs, and customers viewing usage data on the Project Usage page.

What can you expect

• The backlog of pipelines and workflows from the incident has cleared.
• Since about 14:45 UTC, most workflows and jobs are starting within about 15 seconds, and start times are continuing to return to normal.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers monitor the recovery.

Next update We will provide another update by 15:20 UTC.

Identified: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent. Between about 13:00 UTC and 14:40 UTC, workflows and jobs started with delays while we worked through the backlog.

What’s impacted Customers running workflows and jobs, and customers viewing usage data on the Project Usage page.

What can you expect

• The backlog of workflows from pipelines triggered during the incident cleared at about 14:40 UTC.
• Most jobs are now starting within about 30 seconds, and some are waiting up to about 3 minutes.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers continue to work on the underlying issue.

Next update We will provide another update by 15:10 UTC.

Identified: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent.

What's impacted Customers running workflows and jobs, and customers viewing usage data on the Project Usage page.

What can you expect

• Delays starting workflows and jobs are improving. Most jobs are now starting within about 3 minutes, down from about 10 minutes at 13:50 UTC.
• Some workflows from pipelines triggered during the incident are still waiting up to about 40 minutes to start.
• Working through the backlog is taking slightly longer than expected. We now expect to clear it by about 14:45 UTC.
• Workflows from pipelines triggered during the incident are still waiting to start, so retriggering may result in duplicate workflows.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers work to resolve this.

Next update We will provide another update by 15:00 UTC.

Identified: Since 11:15 UTC, customers have experienced disruption to pipelines and notifications. Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent.

What's impacted Customers running workflows and jobs, and customers viewing usage data on the Project Usage page.

What can you expect

• Pipelines are being processed again, including those triggered during the incident.
• Since about 13:25 UTC, workflows and jobs have been starting with increasing delays as we work through the backlog. Most jobs are currently starting within about 10 minutes, and some are waiting up to about 25 minutes.
• We expect to work through this backlog by about 14:35 UTC.
• Workflows from pipelines triggered during the incident are still waiting to start, so retriggering may result in duplicate workflows.
• Usage charge data on the Project Usage page is currently stale.

Thank you for your patience while our engineers work to resolve this.

Next update We will provide another update by 14:30 UTC.

Identified: Between 11:15 UTC and about 13:00 UTC, pipelines were created but not processed, and outbound webhooks and transactional notifications (Slack and email) were not sent.

What's impacted: Customers triggering pipelines, and customers relying on outbound webhooks and email and Slack notifications.

What can you expect:

• Since about 13:00 UTC, pipelines are being processed again and jobs are starting.
• Most jobs are currently starting within about 4 minutes, and some are waiting up to about 10 minutes. Pipelines triggered during the incident are still being processed and may take longer to start.
• Outbound webhooks and notifications have resumed.
• Pipelines are still being processed from the backlog, so retriggering may result in duplicate pipelines.

Thank you for your patience while our engineers work to resolve this.

Next update: We will provide another update by 14:00 UTC.

Identified: What's impacted: Customers triggering pipelines, and customers relying on outbound webhooks and email and Slack notifications.

What can you expect Since 11:15 UTC:

• Pipelines are still being created while this is ongoing but not yet processed, so retriggering may result in duplicate pipelines.
• Outbound webhooks and transactional notifications (Slack and email) are not being sent.
• Pipeline statuses may not be visible.
• Usage charge data on the Project Usage page will be stale.

Thank you for your patience while our engineers work to resolve this.

Next update: We will provide another update by 13:30 UTC.

Identified: There is a delay in our data infrastructure causing delays before build data and some notifications become visible. We are working on a mitigation.