Incident with Pull Requests and Issues
This summary is created by Generative AI and may differ from the actual content.
Overview
Between 16:03 and 16:29 UTC on August 12, 2026, users encountered errors when viewing pull requests, issues, and search results on GitHub.com. About 1.9% of Pull Request requests and 0.9% of Issues requests failed. During a database migration, two indexes were removed while application settings still referenced them, causing affected requests to fail. The issue was detected after the migration reached one database shard and before it progressed to remaining shards. Service was restored by disabling the problematic configuration settings.
Impact
1.9% of Pull Request requests and 0.9% of Issues requests failed during the 26-minute incident window. Search results were also affected, though no specific failure rate was provided.
Trigger
A database migration removed two indexes while application settings still referenced them, causing query failures when requests attempted to use the removed indexes.
Detection
The issue was detected after the migration reached one database shard, before it progressed to the remaining shards. Users reported errors when loading pull request and issue pages, which triggered investigation by engineering teams.
Resolution
The problematic configuration settings that referenced the removed indexes were disabled, which restored service. Engineering teams applied this mitigation and monitored to confirm full resolution.
Root Cause
A mismatch between database schema and application configuration: a database index hint in application settings was referencing an index that had been removed by a recent database migration, causing query failures for affected requests.