On September 25, 2024 from 14:31 UTC to 15:06 UTC the Git Operations service experienced a degradation, leading to 1,381,993 failed git operations. The overall error rate during this period was 4.2%, with a peak error rate of 12.5%. The root cause was traced to a bug in a build script for a component that runs on the file servers that host git repository data. The build script incurred an error that did not cause the overall build process to fail, resulting in a faulty set of artifacts being deployed to production.To mitigate the impact, we rolled back the affecting deployment. To prevent further occurrences of this cause in the future, we will be addressing the underlying cause of the ignored build failure and improving metrics and alerting for the resulting production failure scenarios.
On September 24th, 2024 from 08:20 UTC to 09:04 UTC the Codespaces service experienced an interruption in network connectivity, leading to 175 codespaces being unable to be created or resumed. The overall error rate during this period was 25%. The cause was traced to an interruption in network connectivity caused by SNAT port exhaustion following a deployment, causing individual Codespaces to lose their connection to the service.To mitigate the impact, we increased port allocations to give enough buffer for increased outbound connections shortly after deployments, and will be scaling up our outbound connectivity in the near future, as well as adding improved monitoring of network capacity to prevent future regressions.
On September 16, 2024, between 21:11 UTC and 22:20 UTC, Actions and Pages services were degraded. Customers who deploy Pages from a source branch experienced delayed runs. Approximately 1,100 runs were delayed long enough to get marked as abandoned. The runs that weren't abandoned completed successfully after we recovered from the incident. Actions jobs experienced average delays of 23 minutes, with some jobs experiencing delays as high as 45 minutes. During the course of the incident, 17% of runs were delayed by more than 5 minutes. At peak, as many as 80% of runs experienced delays exceeding 5 minutes. The root cause was a misconfiguration in the service that manages runner connections, which caused CPU throttling and led to a performance degradation in that service.We mitigated the incident by diverting runner connections away from the misconfigured nodes. We are working to improve our internal monitoring and alerting to reduce our time to detection and mitigation of issues like this one in the future.
On September 16, 2024, between 13:24 UTC and 14:28 UTC, the Git Operations service experienced a degradation, leading to intermittent SSH connection drops. The overall SSH error rate during this period was 0.0005%, with a peak error rate of 0.3%.
The root cause was traced to a regression in the service reload mechanism, which resulted in SSH hosts dropping connections on an hourly basis. As SSH hosts were rebooted for routine security updates, the issue progressively affected more hosts.
To mitigate the impact, we removed the affected hosts from production traffic. The SSH regression has since been identified and resolved, with all SSH hosts fully restored. Additionally, we have implemented new monitoring to alert us of any SSH connection refusals moving forward.
On September 14th, 2024 from 20:45 UTC to 22:31 UTC commit creation operations, most commonly Pull Request merges, failed for some repositories. 226 repositories were impacted.The root cause was a hardware fault in a Git file server, where merge commits are calculated. To mitigate the issue we marked the file server as offline.Detection was slower than is typical because of lower weekend traffic. We’re making improvements to monitoring to decrease time to detection in future.
On Sep 13, 2024, between 05:03 UTC and 07:13 UTC, the Webhooks and Actions services were degraded resulting in some customers experiencing delayed processing of Webhooks and Actions Runs. 0.5% of Webhook deliveries were delayed more than 2 minutes during the incident. 15% of Actions Runs started between 05:03 and 05:24 UTC saw run start delays or failures. At 05:24 UTC, we implemented a mitigation to shift traffic to healthy infrastructure and new Actions Runs resumed normal operations. During the rest of the incident window, Actions runs started before 05:24 UTC continued to see delays publishing logs or job results. No Actions runs or Webhook deliveries were lost, only delayed.We mitigated the incident by immediately shifting traffic to a healthy cluster while investigating. The incident was caused by an erroneous configuration change on our eventing platform. A permanent fix was deployed at 06:22 UTC after which services began to recover and burn down their backed up queues, with full recovery by 07:13 UTC.We are working to reduce our time to detection and develop test automation to prevent issues like this one in the future.
Between August 27, 2024, 15:52 UTC and September 5, 2024, 17:26 UTC the GitHub Connect service was degraded. This specifically impacted GHES customers who were enabling GitHub Connect for the first time on a GHES instance. Previously enabled GitHub Connect GHES instances were not impacted by this issue.Customers experiencing this issue would have received a 404 response during GitHub Connect enablement and subsequent messages about a failure to connect. This was due to a recent change in configuration to GitHub Connect which has since been rolled back. Subsequent enablement failures on re-attempts were caused by data corruption which has been remediated. Customers should now be able to enable GitHub Connect successfully.To reduce our time to detection and mitigation of such issues in the future, we are working to improve observability of GitHub Connect failures. We are also making efforts to prevent future misconfiguration of GitHub Connect.
On August 29th, 2024, from 16:56 UTC to 21:42 UTC, we observed an elevated rate of traffic on our public edge, which triggered GitHub’s rate limiting protections. This resulted in <0.1% of users being identified as false-positives, which they experienced as intermittent connection timeouts. At 20:59 UTC the engineering team improved the system to remediate the false-positive identification of user traffic, and return to normal traffic operations.
On August 28, 2024, from 21:40 to 23:43 UTC, up to 25% of unauthenticated dotcom traffic in SE Asia (representing <1% of global traffic) encountered HTTP 500 errors. We observed elevated error rates at one of our global points of presence, where geo-DNS health checks were failing. We identified unhealthy cloud hardware in the region, indicated by abnormal CPU utilization patterns. As a result, we drained the site at 23:26 UTC, which promptly restored normal traffic operations.
On August 28th, 2024, starting at 20:43 UTC, some customers accessing GitHub from North America experienced degraded access to GitHub services. The error was intermittent and manifested as timeouts when requests tried to reach endpoints. This was due to a degraded route internal to one of our transit providers. We identified the unhealthy provider path and drained it at 23:26 UTC, rerouting traffic through other providers and promptly restoring normal traffic operations.