GitHub experienced an authentication outage that disrupted service integrations on June 5, 2026. The issue stemmed from a feature flag enabled between 14:49 UTC and 16:45 UTC, causing authorization failures for legitimate API requests. Engineers turned off the problematic flag, restoring normal authorization behavior for most services.

The outage specifically impacted chat integrations, with customers reporting unexpected repository unsubscription events in their Slack and Teams channels. These subscription disruptions broke automated notifications and workflow triggers that development teams rely on for code review alerts and deployment updates.

GitHub confirmed the degradation has been mitigated and is monitoring system stability. However, the company acknowledged that affected channel subscriptions require manual restoration. Users must re-subscribe their repositories to recover the broken integrations.

Feature flag rollouts remain a common source of production incidents, highlighting the need for better testing protocols before enabling experimental features in live environments. The incident underscores how single configuration changes can cascade across interconnected services.