How to Fix Microsoft 365 Authentication Session Expired Error on Mac
Question details
Users are unable to sign in to Microsoft 365 applications on Mac due to an ongoing 'authentication session expired' error that persists even after basic troubleshooting.
- Product
- Microsoft 365 for Mac
- Device & OS
- macOS
- Scenario
- Attempting to sign in to or activate Microsoft 365 applications on a Mac device.
- Observed behavior
- The application displays an authentication session expired error, blocking access to Office apps despite reinstalling the software and deleting keychains.
Ensure you have your Microsoft account credentials ready and verify that your Microsoft 365 subscription is active by logging into the Microsoft account services portal.
Remove Office License Files and Reinstall Microsoft 365
Clearing old license files removes corrupted activation data that triggers the recurring session expired error.
Often, simply deleting keychains and reinstalling the applications is not enough. The corrupted activation tokens remain deep in the system files until properly wiped using the official license removal tool.
Navigate to account.microsoft.com/services and log in to verify your account has an active Microsoft 365 license.
Download and run the official Microsoft Office License Removal Tool for Mac to clear existing activation files from your system.
Uninstall Microsoft 365 from your Mac, making sure to also delete Office cache files located in the hidden Library folder.
Download the latest version of Microsoft 365 from your account page, install it, and sign in again to activate the software.
Test with a New macOS User Profile
If the issue persists, your current macOS user profile might be corrupted and preventing Office from authenticating properly.
Use WPS Office for Mac as a Hassle-Free Alternative
If Microsoft 365 activation issues persist on your Mac, WPS Office offers a free, lightweight, and highly compatible alternative. Enjoy seamless document editing without complex subscription errors.
- 1. Download WPS Office: Visit the official WPS Office website and download the Mac version.
- 2. Install the Application: Install the software and open your existing Microsoft Office files directly without conversion.
- 3. Start Editing: Begin working immediately with a familiar, tabbed user interface that requires no steep learning curve.
Frequently Asked Questions
Why does my Mac keep saying my Microsoft 365 authentication session expired?
This error usually occurs due to corrupted keychain entries, expired login tokens, or conflicts between old Office license files and your current subscription status.
Will I lose my files if I use the Office License Removal Tool?
No. The Office License Removal Tool only clears activation and licensing data from your Mac. Your personal documents, spreadsheets, and presentations remain untouched.
How do I migrate my data if creating a new Mac user profile fixes the issue?
You can transfer your files by placing them in the Mac's 'Shared' folder (/Users/Shared), or by using an external drive or cloud storage service to move documents from the old profile to the new one.
