Microsoft 365 Alert – Service Degradation – Microsoft 365 suite – Users couldn’t sign in to OneNote class notebooks in OneNote for the web – ONGOING

Announcements Arpan Das

14/01/2026 09:19:00 AM

NHSmail Reference: INC46723449

Microsoft Reference: MO1217505

Issue Status: ONGOING

Issue Description: Users couldn’t sign in to OneNote class notebooks in OneNote for the web.

More info: This issue occurs across multiple browsers and also when using a private browsing mode. This issue also impacts accessing a Class Notebook using the “Manage” option in the OneNote desktop app.

Current Update: 14/01/2026 09:19:00 AM – Microsoft’s investigation has confirmed that a recent update intended to provide optimizations to the pre-authentication flow in the MS Graph API introduced an issue causing an error during authentication and impact. They have reverted this impacting change and are performing validations to confirm it’s successfully remediated impact as expected.

Scope of impact: Your organization is affected by this event, and all users can’t sign in to OneNote class notebooks in OneNote for the web.

Root cause: A recent update intended to provide optimizations to the pre-authentication flow in the MS Graph API introduced an issue causing an error during authentication and impact.

Next update by: Tuesday, January 13, 2026, at 7:30 PM UTC