Three Incidents Served in September
GitHub reported three service disruptions during September 2025, affecting Copilot features, email notifications, and the Copilot API.
Copilot Rate Limiter Misconfiguration
On September 15, between 17:55 and 18:20 UTC, most Copilot features were unavailable for 25 minutes. A partial deployment of a feature flag intended to relax rate limiting for some users instead put the rate limiter into an invalid state, causing it to reject 100% of requests with 403 errors. The team reverted the flag, restoring service immediately.
An undetected edge case in the rate limiting logic was the root cause. In response, GitHub is adding traffic anomaly monitors and expanding rate limit scaling tests to improve pre-production validation.
Email Delivery Delays
Two separate incidents, on September 23 (15:29–17:38 UTC) and September 24 (14:02–15:12 UTC), caused significant delays for most email notification types. Although the combined impact window was roughly 130 minutes, peak customer delays reached about 50 minutes. Unusually high traffic volumes led to resource contention on several outbound email servers.
Configuration changes now aim to better allocate capacity during traffic spikes, and monitoring has been updated to speed up detection of similar conditions.
Copilot API 404 Errors
From September 29, 16:26 to 17:33 UTC, the Copilot API was partially degraded over a 67-minute period, producing intermittent erroneous 404 responses on an average of 0.2% of GitHub MCP server requests, with peaks around 2%. An internal dependency upgrade exposed a service misconfiguration, which was resolved by rolling back the upgrade and fixing the configuration. GitHub is also improving rollout documentation and processes to prevent recurrence.
Live status updates and post-incident summaries are available on the GitHub status page, with engineering details on the GitHub Engineering Blog.
