Disruption with some GitHub services
This summary is created by Generative AI and may differ from the actual content.
Overview
On October 21, 2025, between 13:30 and 17:30 UTC, GitHub Enterprise Cloud Organization SAML Single Sign-On experienced degraded performance, leading to customers being unable to successfully authenticate into their GitHub Organizations. This was caused by a failure in a read replica database partition responsible for storing license usage information. This partition failure resulted in users from affected organizations, whose license usage information was stored on this partition, being unable to access SSO, as a successful SSO requires an available license for the user. The issue was mitigated by taking the failing partition out of service, and remedial actions are currently underway to ensure that a read replica failure does not compromise overall service availability.
Impact
GitHub Enterprise Cloud Organization SAML Single Sign-On experienced degraded performance, with a maximum of 0.4% of SSO requests failing. This prevented affected Enterprise Cloud customers, who had configured SAML at the organization level, from successfully authenticating into their GitHub Organizations.
Trigger
The incident was triggered by a failure in a read replica database partition responsible for storing license usage information for GitHub Enterprise Cloud Organizations. This partition failure directly resulted in users from affected organizations, whose license usage information was stored on this partition, being unable to access SSO.
Detection
GitHub became aware of the issue by observing problems with SAML/OIDC authentication for a small number of GitHub.com users and immediately initiated an investigation.
Resolution
The incident was resolved by taking the failing read replica database partition out of service, which mitigated the degraded performance. Remedial actions are currently underway to ensure that a read replica failure does not compromise overall service availability.
Root Cause
The root cause was a failure in a read replica database partition responsible for storing license usage information for GitHub Enterprise Cloud Organizations. The unavailability of this partition prevented the system from verifying user licenses, which is a prerequisite for successful SAML Single Sign-On, thus blocking authentication for affected users.