On July 26, 2026 at 21:34 UTC we began seeing intermittent errors on the GitHub GraphQL API. A subset of GraphQL API requests returned HTTP 502 errors in short bursts. During the impact window an average of 0.09% of GraphQL API requests in the affected region failed, with a peak of 0.50% of requests failing during the worst two-minute period at 03:02 UTC on July 27. Requests that failed generally succeeded when retried, and no data was lost or altered. Other GitHub services were not affected.
The errors were traced to a single group of servers handling a share of GraphQL API traffic. Application processes on that group intermittently closed connections before completing responses. Impact ended at 03:52 UTC on July 27 when those processes were replaced, and we resolved the incident at 04:09 UTC on July 27 after confirming error rates had returned to normal.
We are still investigating why those processes closed connections, and that work is being carried out by the team that owns the underlying compute platform. In the meantime we are adding detection and automated mitigation for when a single group of servers behaves differently from its peers.
