OneNote Login

Update OneNote and every Microsoft Office app first, then test the notebook online before attempting any credential or notebook reset.

1. Update OneNote without reinstalling again

Downloading Microsoft 365 does not necessarily confirm that all installed apps are current.

• If OneNote opens: select Help > Check for Updates, then install all available Office updates.
• If OneNote closes before you can use its menus:
  • Open another Office app, such as Word, and select Help > Check for Updates; or
  • Open the Mac App Store > Updates if OneNote came from the App Store.

Office apps share sign-in components, so update all of them, not only OneNote.^1^

Because closing and reopening OneNote and reinstalling Microsoft 365 have already failed, do not repeat those steps.

2. Check whether your notes are safe online

Open OneNote for the web and sign in with the Microsoft account normally used in OneNote.

• If the notebook opens and includes the latest notes, the online copy is intact; continue to the sign-in repair below.
• If recent notes are missing, do not delete OneNote, remove its data, or close the affected notebook. Unsynchronized notes could be lost.
• If online sign-in also fails, skip to the activation check.

Also record the complete dialog text, any error code, your macOS version, and the OneNote version under OneNote > About OneNote. “Close OneNote and Try to Fix” alone does not distinguish a startup, activation, keychain, or synchronization problem.

3. Repair the sign-in state

If OneNote remains open long enough to use its menus and your current notes are visible online:

1. Select OneNote > Sign Out.
2. Quit OneNote.
3. Reopen it and select OneNote > Sign In.
4. Use the same account that successfully opened the notebook online.

If OneNote reports a notebook connection or synchronization problem afterward:

1. Confirm again that the latest notes are visible online.
2. In OneNote, select File > Close This Notebook.
3. Select File > Open Recent, then reopen the notebook.

Microsoft documents closing and reopening a notebook as a way to reset its connection, but it should not be done when unsynchronized changes have not been backed up.^2^

4. If macOS repeatedly requests keychain access

If the actual message mentions Keychain, Authentication Session Expired, or repeatedly asks you to sign in:

1. Quit Word, Excel, PowerPoint, Outlook, and OneNote.
2. Confirm the Office applications are in the Mac’s Applications folder.
3. When macOS asks for keychain access, select Always Allow.
4. If prompts continue, restore Office’s keychain permissions using the Apple procedure linked from Microsoft’s keychain support article.^3^

Avoid deleting arbitrary Keychain entries. The older Microsoft workaround involving Office15 credentials was written for OneNote 2016 and should not be the first repair method for a current Microsoft 365 installation.

5. If this is an activation failure

Confirm that you are signing in with the account associated with the Microsoft 365 purchase. Then run Microsoft’s Microsoft 365 Activation troubleshooter, which is the activation repair linked from the Office for Mac guidance.^4^

If OneNote cannot remain open long enough to access its menus, or these steps fail, use Contact Us at the bottom of Microsoft’s OneNote issues page.^1^ Provide the complete message or screenshot, error code, macOS and OneNote versions, and whether Word or Excel can sign in successfully.

References

1. Fixes or workarounds for recent issues in OneNote for Mac, iPhone, and iPad | Microsoft Support
2. Mac
3. Office for Mac repeatedly requesting keychain access | Microsoft Support
4. Activation