Incident with GitHub.com

Lesson: Engineering teams should subscribe to platform status updates to remain informed during service incidents.

What happened

On August 17, 2026, from 13:28–21:15 UTC (7h 47m), GitHub.com experienced elevated errors and latency across Issues, Pull Requests, APIs, Actions, and Copilot. At peak, web/API error rates were approximately 20%, while archive and raw-content downloads reached approximately 50%. SAML/OIDC authentication, SCIM, and Team Sync were also affected, as well as Actions workflows in GHEC with Data Residency that depend on public workflow step definitions hosted on GitHub.com. Most services recovered by 16:36 UTC as our Central US datacenter recovered; Actions was degraded until approximately 18:03 UTC; and Copilot Token Service fully recovered by 21:02. Some of the failing traffic was moved from Central US to Northern Virginia where it was served successfully until the network failure in Central US was debugged and resolved. Delayed replies to a single internal endpoint triggered a latent retry bug in VS Code that amplified traffic by approximately 10x and caused delayed recovery for the Copilot Token Service. The immediate cause of the failure was network saturation on load balancers in Central US due to a new peak in traffic. Originally this was caused by an Istio sidecar pod reaching

1. Resolved · Aug 17, 21:15 UTC
   On August 17, 2026, from 13:28–21:15 UTC (7h 47m), GitHub.com experienced elevated errors and latency across Issues, Pull Requests, APIs, Actions, and Copilot. At peak, web/API error rates were approximately 20%, while archive and raw-content downloads reached approximately 50%. SAML/OIDC authentication, SCIM, and Team Sync were also affected, as well as Actions workflows in GHEC with Data Residency that depend on public workflow step definitions hosted on GitHub.com. Most services recovered by 16:36 UTC as our Central US datacenter recovered; Actions was degraded until approximately 18:03 UTC; and Copilot Token Service fully recovered by 21:02. Some of the failing traffic was moved from Central US to Northern Virginia where it was served successfully until the network failure in Central US was debugged and resolved. Delayed replies to a single internal endpoint triggered a latent retry bug in VS Code that amplified traffic by approximately 10x and caused delayed recovery for the Copilot Token Service. The immediate cause of the failure was network saturation on load balancers in Central US due to a new peak in traffic. Originally this was caused by an Istio sidecar pod reaching its concurrency limits and failing to auto scale correctly because of a misconfigured policy that watched host service but not sidecar limits. One failure cascaded to more and eventually four HAProxy nodes exhausted their flow limits, degrading the gateway auth path and causing widespread authentica
2. Investigating · Aug 17, 20:45 UTC
   We are continuing to apply mitigations to address sporadic Copilot authentication failures in some applications. We expect full recovery within the next 30 minutes. Copilot usage via the GitHub CLI and GitHub App are unaffected.
3. Investigating · Aug 17, 20:22 UTC
   Issues is operating normally.
4. Investigating · Aug 17, 20:08 UTC
   We are continuing to investigate sporadic failures affecting Copilot authentication in some applications. Copilot usage via the GitHub CLI and GitHub App are unaffected.
5. Investigating · Aug 17, 19:13 UTC
   We are continuing to investigate sporadic authentication failures. We have partially disabled authentication token retries and have seen improvement, and we are monitoring impact before fully applying this mitigation.
6. Investigating · Aug 17, 19:01 UTC
   API Requests is operating normally.
7. Investigating · Aug 17, 18:48 UTC
   API Requests is experiencing degraded availability. We are continuing to investigate.
8. Investigating · Aug 17, 18:23 UTC
   The degradation affecting Git Operations has been mitigated. We are monitoring to ensure stability.
9. Investigating · Aug 17, 18:11 UTC
   We identified the problematic component and have taken corrective actions, but we are seeing residual impact in the form of sporadic authentication failures. We are continuing to apply additional mitigations and investigate the remaining impact.
10. Investigating · Aug 17, 17:36 UTC
    Issues is experiencing degraded performance. We are continuing to investigate.
11. Investigating · Aug 17, 17:34 UTC
    We identified the problematic component and have taken corrective actions, but we are seeing residual impact across numerous services. We are continuing to apply additional mitigations and investigate the remaining impact.
12. Investigating · Aug 17, 17:30 UTC
    Git Operations is experiencing degraded performance. We are continuing to investigate.
13. Investigating · Aug 17, 16:59 UTC
    The degradation affecting API Requests, Actions, Git Operations, Issues, Pages, Pull Requests and Webhooks has been mitigated. We are monitoring to ensure stability.
14. Investigating · Aug 17, 16:36 UTC
    We identified the problematic component and have taken corrective actions. There are strong signs of recovery but we are still working to completely restore service, with error rates still remaining slightly elevated. We will post further updates as recovery continues.
15. Investigating · Aug 17, 16:16 UTC
    We are experiencing high error rates around 20% for web experiences and api traffic. Archive downloads and raw repository content downloads are experiencing an approximate 50% error rate. SAML and OIDC authentication, SCIM, and Team Sync are also impacted. We are still working to identify the root cause and will continue to post updates as we learn more and perform mitigation.
16. Investigating · Aug 17, 15:42 UTC
    We are experiencing high error rates around 20% for web experiences and api traffic. Archive downloads and raw repository content downloads are experiencing an approximate 50% error rate. SAML and OIDC authentication, SCIM, and Team Sync are also impacted. We are currently performing mitigations and will post updates as we progress.