Microsoft 365 Alert – Service Degradation – SharePoint Online – Some users may be unable to load pages with custom apps or webparts in SharePoint Online and get an error – RESOLVED

Announcements Arpan Das

19/11/2025 09:37:00 AM

NHSmail Reference: INC46685534

Microsoft Reference: SP1187718

Issue Status: RESOLVED

Issue Description: Users may be unable to load pages with custom apps or webparts in SharePoint Online and get an error.

More info: The following error may be encountered by users when attempting to load an affected page:
An error occurred during the compilation of the requested file, or one of its dependencies. ‘Microsoft.SharePoint.IdentityModel.SPAuthFlightController’ does not contain a definition for ‘IsRemoveRedirectWithProofTokenOnSignInPageEnabled’

Final Update: 25/11/2025 08:25:00 AM – Microsoft have completed the deployment of their fix and confirmed that impact has been fully resolved for all users.

Scope of impact: Some users may be unable to load pages with custom apps or webparts in SharePoint Online and get an error. This section may be updated as our investigation continues.

Root cause: A recent change intended to update the authentication flow has mistakenly removed a necessary authentication component, resulting in impact.

Next steps: Microsoft are reviewing their change testing and validation procedures to identify opportunities to improve impact detection and prevent similar future occurrences.