Title: Users may be unable to sign in to OneNote using iOS devices User impact: Users may be unable to sign in to OneNote using iOS devices. More info: Impact is specific to users with OneNote build 16.112.717.0 or higher. Whilst we work on remediation, impacted users may be able to utilize OneNote on the web or remove Authenticator so that authentication falls back to the in-app webview. Users may also be able to sign in to any other Microsoft 365 apps first (e.g. PowerPoint), then attempt to sign in again in OneNote. Current status: We've identified that a code change included in OneNote builds 16.112.717.0 and above, designed to change how authentication requests are routed, introduced an issue with OneNote iOS Authenticator broker sign-in and is causing impact. We're deploying a code fix to correct this issue and expect that it'll complete deployment by the time of our next update. Scope of impact: Any user attempting to sign in to OneNote build 16.112.717.0 or higher using iOS devices is impacted. Start time: Monday, July 20, 2026, at 4:36 AM UTC Root cause: A code change included in OneNote builds 16.112.717.0 and above, designed to change how authentication requests are routed, introduced an issue with OneNote iOS Authenticator broker sign-in and is causing impact. Next update by: Tuesday, August 18, 2026, at 6:00 AM UTC

We're aware of a possible issue with reporting. We are aware and aim to resolve the issue as quickly as possible. We apologize for any inconvenience that this may have caused.

We are currently investigating an issue affecting SMS delivery due to a service disruption with an upstream infrastructure partner. Impact: Messages may remain in your outbox with a "sending" status for longer than usual, or they may fail to deliver entirely. We are actively working with our partner to restore full service.