Dear @Rose,
Thank you for providing those details. I understand how frustrating this situation must be, especially since you're able to access the same Microsoft account successfully through OneNote on your phone, laptop, and the web version.
Since the issue appears to be isolated to the OneNote app on your iPad, I'd like to gather a bit more information to help narrow down the cause:
- What version of iPadOS is currently installed on your iPad?
- Does the issue occur on both Wi-Fi and a different network connection, such as a mobile hotspot?
- When the sign-in fails, do you consistently receive the "Microsoft account doesn't exist" message, or does the app simply return to the sign-in screen without any error?
In the meantime, please follow the steps below:
Note: Before following the steps ensure there are no changed you made in OneNote for iPad which are not synced yet. The steps below will close all your notebooks and log you out from the OneNote app.
- Please check whether both your iPadOS and the OneNote app are fully up to date, as outdated versions can sometimes cause authentication issues on iOS devices.
- If OneNote is currently running on the iPad, force the app to close by double-tapping the Home button on the iPad, and then swiping up on the OneNote app preview.
- On your iPad, tap the Settings app. In the pane on the left, scroll down to the alphabetical list of installed apps and then tap the OneNote icon.
- In the OneNote options on the right, under the Reset heading, tap Reset OneNote.
- In the Reset OneNote options on the right, tap to enable the Delete All Notebooks option, and then also tap to enable the Delete Login Credentials option.
- Restart OneNote, and then tap Sign In to log in with your work or school credentials.
Thank you for your patience and cooperation, and I look forward to your update. Hope you having a nice day and really much warm regards to you as well!
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