Auth issue resulting in API impacts, including some Slack and Teams channel subscriptions

Final update

On June 5, 2026, between 15:35 UTC and 16:45 UTC, 0.11% of authenticated REST API requests incorrectly returned “not found” responses. Impact was concentrated among - and significantly higher for - users authenticating with user-to-server tokens to access organization-owned repositories. Some users of our GitHub for Slack and GitHub for Microsoft Teams integrations saw their channel subscriptions removed as those systems interpreted the transient "not found" response as durable loss of access. Roughly 12% of organizations with active channel subscriptions were impacted, with ~2% of all channel subscriptions being removed. These issues were triggered by a change to an internal authorization component that did not correctly resolve access for user-to-server tokens against organization-owned repositories. We mitigated the incident by disabling the accompanying feature flag at 16:45 UTC, after which API responses returned to normal. We then restored all impacted Slack and Microsoft Teams channel subscriptions, with restoration completed at 22:21 UTC. We are working to add retry and grace-period logic in the chat integrations so transient errors no longer trigger subscription deletions.

1. Resolved · Jun 5, 22:21 UTC
   On June 5, 2026, between 15:35 UTC and 16:45 UTC, 0.11% of authenticated REST API requests incorrectly returned “not found” responses. Impact was concentrated among - and significantly higher for - users authenticating with user-to-server tokens to access organization-owned repositories. Some users of our GitHub for Slack and GitHub for Microsoft Teams integrations saw their channel subscriptions removed as those systems interpreted the transient "not found" response as durable loss of access. Roughly 12% of organizations with active channel subscriptions were impacted, with ~2% of all channel subscriptions being removed. These issues were triggered by a change to an internal authorization component that did not correctly resolve access for user-to-server tokens against organization-owned repositories. We mitigated the incident by disabling the accompanying feature flag at 16:45 UTC, after which API responses returned to normal. We then restored all impacted Slack and Microsoft Teams channel subscriptions, with restoration completed at 22:21 UTC. We are working to add retry and grace-period logic in the chat integrations so transient errors no longer trigger subscription deletions. In parallel, we are improving observability and gating of authorization changes so downstream impact is detected during scoped, gradual rollouts.