GitHub Service Incident: Delays Caused by Database Migration Replication Lag (May 12, 2026)
By
cebert
5d ago· 2 min readen
55/100
Doughy
Bagelometer↗
Slightly gummy. The crust never quite set.
Score55Typepress releaseSentimentnegative
Summary
GitHub experienced a service incident on May 12, 2026, where between 13:41 and 17:43 UTC, several services faced delays. Code Scanning had 53% of check runs taking over 15 minutes, notifications averaged 22 minutes delivery delay, and Slack integration webhooks averaged 20 minutes delay. The root cause was replication lag from an internal database migration causing insufficient worker capacity. The issue was mitigated by scaling processing workers.
Key quotes
· 4 pulledOn May 12, 2026, between 13:41 and 17:43 UTC, some services experienced delays in processing.
For the Code Scanning service, 53% of check runs took over 15 minutes to complete.
The delays were caused by replication lag due to an internal database migration, resulting in insufficient worker capacity for our high rate of job enqueues.
We mitigated the impact by scaling our processing workers to handle the increased load.
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