OneNote Sign-In window is stuck on Loading...

Hi,

Do the other apps allow you to sign in like Outlook?

Try https://office-reset.com/ to clear Keychain entries related to Microsoft office.

I’m eager to hear back and work together to find a solution.

Standard 3rd party link disclaimer:

There may be links to non-Microsoft websites that provide accurate and safe information. Watch out for ads on websites frequently classified as PUP (Potentially Unwanted Products). There is no need to buy paid products to fix your computers, as they sometimes do more harm than good.

To fix the stuck “Loading…” sign-in window for OneNote on macOS, use the macOS-specific steps to clear and rebuild Office/OneNote credentials, then sign in again.

Follow these steps in order:

1. Update OneNote and all Office apps
   • If OneNote was installed from the Mac App Store:
     • Open App Store > Updates and install updates for Microsoft OneNote and any other Microsoft Office apps.
   • If OneNote was installed as part of Microsoft 365/Office for Mac:
     • Open OneNote.
     • Go to Help > Check for Updates.
     • In Microsoft AutoUpdate, install all available updates for Office apps.
   • Make sure Word, Excel, PowerPoint, Outlook (if installed) are all updated, because they share the same identity/keychain items.
2. Clear corrupted Office credentials from macOS Keychain
   • Quit all Office apps except OneNote.
   • In OneNote, sign out of all accounts:
     • Use OneNote > Sign Out.
     • This only signs out; notebooks remain on disk/cloud.
   • Quit OneNote.
   • Open Keychain Access (from Applications > Utilities).
   • In the search box, type Office15.
   • For each item whose Kind starts with MicrosoftOffice15… (one per account typically):
     • Select it and delete it.
   • This removes only authentication credentials, not notebook data. They will be recreated on next sign-in.
3. Restart and sign in again
   • Restart the Mac.
   • Open OneNote.
   • When prompted, sign in with the correct Microsoft account.
   • If the sign-in window appears, it should now allow credential entry instead of staying on “Loading…”.
4. If sign-in loops or prompts repeatedly
   • On iOS devices using the same account (if applicable), clear credentials as well to avoid corrupt identity being reused:
     • Go to iOS Settings > OneNote > Reset OneNote > enable Delete Sign-In Credentials.
     • Force-quit OneNote on iOS, then reopen and sign in again.

If the issue persists after these steps, repeat the Keychain cleanup to ensure all MicrosoftOffice15… items are removed, then update and sign in again.

References:

• Fixes or workarounds for recent issues in OneNote for Mac, iPhone, and iPad
• Fix issues when you can't sync OneNote
• Sign-in problems for work or school accounts on OneNote for Windows
• Connection issues when signing in after updating to Office 2016 build 16.0.7967 on Windows 10