CCR and CCA failing to start for PR comments

Lesson: Engineering teams should ensure detailed incident analysis and root cause information are documented during service failures.

What happened

On May 7, 2026, between 04:12 UTC and 06:13 UTC, Copilot Cloud Agent and Copilot Code Review Agent sessions for pull requests were delayed or failed to start. The issue was caused by follow-up recovery work from a separate Pull Requests incident (https://www.githubstatus.com/incidents/f5pb5d5mr9yh). As part of that recovery, we ran a large database migration, which caused replication delays on several replica hosts. Although those replicas were not serving user traffic, our safeguards correctly treated the elevated replication lag as a signal to slow down writes to the affected database cluster. As a result, some pull request background processing was temporarily delayed. That processing is responsible for sending the internal events that Copilot agents use to begin work, so affected agents did not start until the database replicas caught up. The system recovered once replication lag returned to normal and pull request processing resumed. We are reviewing how this safeguard interacts with recovery migrations so we can reduce the chance of similar secondary impact during future incident recovery work.

1. Resolved · May 7, 06:56 UTC
   On May 7, 2026, between 04:12 UTC and 06:13 UTC, Copilot Cloud Agent and Copilot Code Review Agent sessions for pull requests were delayed or failed to start. The issue was caused by follow-up recovery work from a separate Pull Requests incident (https://www.githubstatus.com/incidents/f5pb5d5mr9yh). As part of that recovery, we ran a large database migration, which caused replication delays on several replica hosts. Although those replicas were not serving user traffic, our safeguards correctly treated the elevated replication lag as a signal to slow down writes to the affected database cluster. As a result, some pull request background processing was temporarily delayed. That processing is responsible for sending the internal events that Copilot agents use to begin work, so affected agents did not start until the database replicas caught up. The system recovered once replication lag returned to normal and pull request processing resumed. We are reviewing how this safeguard interacts with recovery migrations so we can reduce the chance of similar secondary impact during future incident recovery work.