Office for Mac Issues

How to Fix Office Activation Errors on Mac with Another Account Signed In

Maira Mehtab Oct 15, 2026 869 views

Question details

The user is unable to activate Microsoft 365 on a Mac because the system states another organizational account is already signed in.

How to Fix Office Activation Errors on Mac with Another Account Signed In

Product: Microsoft 365 for Mac
Device & OS: macOS
Scenario: Activating Microsoft Office after changing employers, schools, or switching Microsoft 365 subscription accounts.
Observed behavior: An error message blocks activation by claiming another account is already signed in, preventing the use of the new account credentials.

Before you start

Ensure you have your new Microsoft 365 account credentials ready and verify that all Microsoft Office applications (Word, Excel, PowerPoint, Outlook) are completely closed before starting.

Solution 1Recommended

Clear Microsoft Office Group Containers Cache

Removing the cached library files forces Office to reset its activation state and forget the old organizational account.

macOS stores application data and activation states in the Group Containers folder. Clearing specific Microsoft files from this directory is the most effective way to remove stuck account profiles.

Close Applications

Quit all running Office applications on your Mac.

Open Go to Folder

Click anywhere on your desktop to activate Finder, then select 'Go' > 'Go to Folder' from the top menu bar.

Locate Group Containers

Type ~/Library/Group Containers in the search box and press Return.

Delete Office Cache Folders

Locate and move the following folders to the Trash if they are present: UBF8T346G9.ms, UBF8T346G9.Office, and UBF8T346G9.OfficeOsfWebHost.

Reactivate Office

Open Word or Excel and try signing in again with your new Microsoft 365 account.

Clear Microsoft Office Group Containers Cache

Outlook Data: Moving the UBF8T346G9.Office folder will also remove your Outlook profiles and custom templates. If you use Outlook for Mac, back up your local data first.

Solution 2

Remove Office Credentials from Keychain Access

If resetting the Group Containers doesn't work, macOS might still be holding onto old Microsoft login tokens in your system Keychain.

Solution 3

Test on a New Mac User Profile

If the issue persists in your primary account, a corrupted user profile may be causing the activation loop.

Free Microsoft Office alternative

Avoid Activation Hassles with WPS Office for Mac

If Microsoft 365 activation loops are preventing you from getting work done, consider switching to WPS Office. It provides a lightweight, highly compatible alternative for Mac users without complex subscription or organizational account lockouts.

1. Download for Mac: Visit the official WPS Office website and download the macOS version.
2. Install Seamlessly: Open the downloaded installer file and drag the WPS Office icon into your Applications folder.
3. Open and Edit Immediately: Double-click any existing Microsoft Office document to open and edit it instantly without signing into an organizational account.

Completely free to download and use for essential office tasks, bypassing activation errors.Highly compatible with Microsoft Office file formats, including .docx, .xlsx, and .pptx.Lightweight macOS installation that won't clutter your storage or system Keychain.An intuitive, all-in-one tabbed interface for managing documents, spreadsheets, and presentations.

microsoft office alternative - wps office

Frequently Asked Questions

Why does Microsoft Office say another account is already signed in?

This occurs when your Mac retains cached login tokens from a previous employer, school, or secondary Microsoft 365 account in its local Keychain or Group Containers directory.

Will I lose my personal files if I delete the Office Group Containers?

Your actual Word, Excel, and PowerPoint documents saved in standard folders (like Documents or Desktop) will remain completely safe. However, deleting these folders will clear locally cached Outlook profiles and custom Office templates if they are not backed up.

What should I do if the activation error only happens on one Mac user account?

If Office activates successfully on a newly created Mac profile but fails on your old one, the issue is tied to your old profile's cache. You must either successfully clear the old profile's Keychain and cache, or manually migrate your files to the new working Mac user account.

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