Auth issue resulting in API impacts, including some Slack and Teams channel subscriptions
Incident
Report for GitHub
Resolved
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.
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.
Update
Affected Slack and Teams subscriptions have been restored. Please contact support if you encounter any additional issues.
Update
Additional detail on the scope of impact during the 14:49 UTC to 16:45 UTC window: a small but elevated percentage of authenticated requests to GitHub.com received incorrect authorization failures. We saw a 1 to 2% increase in 4xx responses for a small number of endpoints (/repos/{owner}/{repo}/pulls/{pull_number}, /repos/{owner}/{repo}, /repos/{owner}/{repo}/contents/{path}). The vast majority of requests completed normally; customers who saw errors during the window can retry now and should see them succeed.
Update
We are still exploring options to restore the deleted subscriptions, and we will provide another update soon. In the meantime, customers can manually re-subscribe their Slack and Teams channels to repositories.
Monitoring
The degradation has been mitigated. We are monitoring to ensure stability.
Update
During 14:49 UTC to 16:45 UTC, customers may have experienced authorization failures for legitimate requests. This was caused by a recently enabled feature flag, which has now been turned off as a mitigation. Customers should now see normal authorization behavior. This is also the cause of the chat integration issue, and we are exploring options to restore it. In the meantime, customers can manually re-subscribe their repo.
Update
Customers may see unexpected repo unsubscription events in their Slack or Teams channels.
Investigating
We are investigating reports of impacted performance for some GitHub services.
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