Some users were unable to sign in to OneNote using iOS devices

Title: Some users were unable to sign in to OneNote using iOS devices

User impact: Users were unable to sign in to OneNote using iOS devices.

More info: Impact was specific to any user with OneNote build 16.112.717.0 or higher.

Whilst we were working on remediation, some impacted users were able to utilize OneNote on the web or remove Authenticator so that authentication falls back to the in-app webview. Some users were also able to sign in to any other Microsoft 365 apps first (e.g. PowerPoint), then attempt to sign in again in OneNote.

Final status: We've completed deployment of the fix and confirmed with your organization that impact has been resolved.

Scope of impact: Any user attempting to sign in to OneNote build 16.112.717.0 or higher using iOS devices was impacted.

Start time: Monday, July 20, 2026, at 4:36 AM UTC

End time: Monday, August 31, 2026, at 12:00 AM UTC

Root cause: A code change included in OneNote builds 16.112.717.0 and above, designed to change how authentication requests were routed, introduced an issue with OneNote iOS Authenticator broker sign-in and caused impact.

Next steps:
- We're reviewing our deployment and validation processes to help prevent similar issues from occurring in the future.

This is the final update for the event.

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 completed the validation of our fix in our internal testing environment and are preparing it for deployment, which should complete by our next scheduled update. Additionally, we've received confirmation from a subset of users who reported the issue that the fix resolves impact.

Scope of impact: Any user attempting to sign in to OneNote build 16.112.717.0 or higher using iOS devices is impacted. This information may be updated as our investigation continues.

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: Thursday, September 17, 2026, at 10:00 AM UTC

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: Current status: We're progressing with the validation of our fix in our internal testing environment. Additionally, we're continuing to await confirmation from a subset of users who reported the issue and have received the fix to help with validating its efficacy so we can proceed with its full release.

Scope of impact: Any user attempting to sign in to OneNote build 16.112.717.0 or higher using iOS devices is impacted. This information may be updated as our investigation continues.

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: Thursday, September 3, 2026, at 10:00 AM UTC

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: Validating the efficiency of the fix is taking longer than expected. We're continuing with the validations in our internal testing environment, and we've released the new version containing the fix to a subset of users who reported the issue to help with validating if it remediates impact as expected.

Scope of impact: Any user attempting to sign in to OneNote build 16.112.717.0 or higher using iOS devices is impacted. This information may be updated as our investigation continues.

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: Wednesday, September 2, 2026, at 10:00 AM UTC

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 additional testing and validations are required in order to ensure the issue is resolved without adversely impacting other aspects of the service. We've halted the release, and we're deploying it to our internal testing environment for additional validation before releasing it to the app store. Once our validations are complete, we'll aim to provide a new timeline for when we expect the deployment to be available in the App store.

Scope of impact: Any user attempting to sign in to OneNote build 16.112.717.0 or higher using iOS devices is impacted. This information may be updated as our investigation continues.

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, September 1, 2026, at 6:00 AM UTC

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 confirmed that the fix will be part of the updated version of the OneNote app on iOS and are monitoring its implementation on the App Store. Once available, we'll confirm that the updated version remediates the impact.

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 25, 2026, at 6:00 AM UTC

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’re continuing to monitor our fix deployments progress as it continues to saturate throughout the affected environment. Additionally, we expect that a remediation timeline will be provided by our next scheduled 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: Monday, August 24, 2026, at 6:00 AM UTC

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: Our fix deployment is taking longer than anticipated but is ongoing. We're continuing to monitor as it progresses to establish a completion timeline.

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: Friday, August 21, 2026, at 4:00 AM UTC

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

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 an issue with the OneNote iOS Authenticator broker sign-in and are working on developing and validating a fix to remediate impact.

Scope of impact: Any user attempting to sign in to OneNote build 16.112.717.0 or higher using iOS devices is impacted.

Root cause: An issue with the OneNote iOS Authenticator broker sign-in is preventing users from signing in to OneNote using iOS devices.

Next update by: Friday, August 14, 2026, at 4:00 PM UTC

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.

Current status: We've identified that a recent change to the sign in flow may be causing impact to occur. We've reverted the change but this did not resolve the issue. We're analyzing OneNote logs from impacted users as well as OneNote logs from our internal reproduction of the issue to assist us in identifying the underlying root cause of impact.

Scope of impact: Any user attempting to sign in to OneNote build 16.112.717.0 or higher using iOS devices is impacted.

Next update by: Friday, August 14, 2026, at 2:00 PM UTC