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Fix WebDAV Basic Authentication Issue in Office for Mac 16.84
Question details
After upgrading to Office for Mac 16.84, Word fails to authenticate with WebDAV servers, sending an empty Bearer header instead of Basic authentication.
- Product
- Microsoft Office for Mac
- Device & OS
- macOS
- Scenario
- Accessing, opening, or saving files to a WebDAV server using Office for Mac version 16.84.
- Observed behavior
- Word prompts for a sign-in but does not transmit credentials, sending an empty Bearer authorization header instead of the expected Basic authentication header.
Ensure you have your WebDAV server credentials handy and administrative access to your Mac, as you will need to uninstall the current software and reinstall a previous version.
Roll Back to Office for Mac Version 16.81
Since the issue is a bug introduced in version 16.84, reverting to the stable 16.81 version will immediately restore WebDAV Basic authentication functionality.
Microsoft Office update 16.84 handles WebDAV authentication headers incorrectly. Downgrading bypasses the bug until a permanent patch is released.
Open the Applications folder on your Mac, locate the Microsoft Word application, and drag it to the Trash. Repeat for other Office apps if necessary.
Navigate to the official Microsoft Office for Mac update history webpage and download the installer package for version 16.81.
Run the downloaded installer package and follow the on-screen prompts to complete the reinstallation of Office for Mac 16.81.
Open Word, go to Help > Check for Updates in the top menu bar, and uncheck the automatic update option to prevent the system from automatically upgrading back to the broken 16.84 version.
Report the Issue to Microsoft 365 Support
Escalate the bug directly to Microsoft so their engineering team can investigate and patch the authorization header bug in a future release.
Try WPS Office for Mac for Seamless File Management
If Office for Mac 16.84 is disrupting your workflow with WebDAV server errors, consider switching to WPS Office. It is a lightweight, free alternative that offers excellent compatibility with Microsoft Office formats and provides reliable file management without the authentication bugs of recent updates.
Frequently Asked Questions
Why does Office for Mac 16.84 prompt for sign-in but fail to connect to WebDAV?
Version 16.84 introduced a compatibility bug where the application attempts to use an empty Bearer authorization header instead of Basic authentication. As a result, your typed credentials are never actually transmitted to the WebDAV server.
Can I fix the WebDAV authentication issue without downgrading my Office version?
Currently, there is no built-in toggle or terminal command in version 16.84 to force Basic authentication over the broken Bearer header. Downgrading to version 16.81 is the most reliable workaround until Microsoft issues an official patch.
Will downgrading to Office 16.81 delete my Word documents or Mac files?
No. Uninstalling the Office applications and installing an older version only replaces the application files. It does not affect your personal documents, settings, or files stored locally on your Mac or your WebDAV server.
