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issue with an Apple (macOS) user

Mohamed Aburayya 20 Reputation points
2026-06-07T11:29:03.7433333+00:00

Hello,

I am facing an issue with an Apple (macOS) user in our organization.

We recently migrated from our old Microsoft 365 tenant to a new tenant. However, on this user’s Mac device, whenever they try to sign in to Outlook or any Office application using their account from the new tenant, the sign-in process keeps redirecting them to their account from the old tenant.

We have already removed old accounts from the Office apps and tried signing out and signing back in, but the issue persists.

Has anyone experienced a similar issue on macOS? Are there any cached credentials, keychain entries, or device settings that could still be forcing authentication against the old tenant?

Any guidance would be appreciated.

Thank you.

Microsoft 365 and Office | Install, redeem, activate | For business | MacOS
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Answer accepted by question author

Michelle-N 17,370 Reputation points Microsoft External Staff Moderator
2026-06-07T17:23:56.4166667+00:00

Hi @Mohamed Aburayya

Based on the information you shared, I understand that after a recent tenant migration, a macOS user is experiencing a sign-in loop where Office applications continuously redirect them to the old tenant's authentication interface, even after manually removing the accounts from the apps.

This behavior is quite common on macOS because Office deeply caches authentication tokens, licensing states, and tenant configuration data within the local system library and Keychain.

To clear this cached state and successfully connect to the new tenant, please follow the steps below:

Before attempting to sign in again, you need to completely flush the old tenant's cached identity and licensing state from the device. Microsoft provides a dedicated utility that handles this cleanly without affecting the actual application installations:

How to remove Office license files on a Mac

To help narrow down whether this is strictly a local macOS device caching issue or an account/tenant propagation issue, could you please check the following:

-Is the user able to successfully log in to the Office Web App using their new tenant account?

Please give the License Removal Tool a try, let me know if it successfully clears the redirection loop, and keep me updated on the web login results so we can investigate further if needed.

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  1. AI answer

    2026-06-07T11:29:18.9433333+00:00

    On macOS, cached Office/OneAuth credentials and Keychain entries can cause Office apps to keep using an old Microsoft 365 tenant account even after a tenant migration.

    To force Outlook and other Office apps to stop authenticating against the old tenant on Mac, use these steps:

    1. Close all Microsoft 365 apps (Outlook, Word, Excel, Teams, etc.).
    2. Reset the Office/OneAuth credentials for Mac:
      • Open Terminal and run: 
             defaults write com.microsoft.Word ResetOneAuthCreds -bool YES
      • Then open Microsoft Word and go through the sign-in/activation flow with the new-tenant account.
    3. Clear old Office-related credentials from Keychain:
      • Open Keychain Access.
      • In the search box, type Office.
      • Delete all entries that contain “Office” (typically between two and six entries).
      • Optionally also search for and remove entries related to Microsoft, ADAL, and MSOID if they are clearly tied to the old account.
      • Close Keychain Access.
    4. Reopen Outlook/Office apps and sign in only with the new-tenant account.

    These steps remove the cached sign-in data and force the apps to authenticate cleanly against the new tenant instead of reusing the old tenant’s tokens.

    References:

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