How to resolve "The server you are trying to access is using an authentication protocol not supported by this version of Office"?

1. Exit the OneDrive for Business application. Then open Task Manager and make sure the groove.exe process is no longer running. Otherwise, end the process through Task Manager.

   End the msosync.exe process through Task Manager.

   This is necessary, because we need to delete data that is accessed by these processes.

2. Open Credential Manager from the Control Panel, switch to the Windows Credentials section and delete all stored credentials that refer to MicrosoftOffice.

   

3. Open the Registry Editor (regedit.exe) and navigate to the Office 2016 branch at HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Internet. If a Server Cache key exists here, delete it.

   If you had older versions of Office installed at some point, delete the same key in their respective branches. For example: HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Common\Internet\Server Cache

4. Navigate to the AppData folder associated with Office 2016 at %LOCALAPPDATA%\Microsoft\Office\16.0\ If a Spw folder exists here, delete it.

   In the same folder, delete the contents of the OfficeFileCache folder.

   If you had older versions of Office installed at some point, repeat the same steps in the respective folders. For example: %LOCALAPPDATA%\Microsoft\Office\15.0\

5. Log in at https://portal.office.com and enter your OneDrive. Click the Synchronize link in the toolbar to invoke synchronization in OneDrive for Business.

The accepted answer did not work for me, but the workaround here did:

1. End the GROOVE and MSOSYNC processes.
2. Open Word / Excel / PowerPoint (or any Office app that is not OneDrive For Business).
3. Click the Switch Account at the top right.
4. Click Add Account.
5. Add the account that you actually need to sync that particular library.
6. Close the application.
7. Close OneDrive for Business. (You need to actually right click in the taskbar and click Exit).
8. Open OneDrive, and attempt to sync the library. You should not be prompted with the error message.

If these steps do not work, please remove all signed in accounts, and then attempt to sync the library which should prompt appropriately. After the library syncs, feel free to add those identities back.

What I did for this particular situation was to disconnect my OneDrive account from one drive for business on my computer. go to this site https://onedrive.live.com/about/en-us/download/ and click start one drive.

For me the fix for this was updating my OneDrive client.

I tried both fixes mentioned but they didn't work no matter how many cache or client cred removals I did. Whenever I got to the final step and tried to sync via portal.office.com > OneDrive, it couldn't find the app installed (even though it was there running).

When trying to sync, clicking the "get the latest version of OneDrive" ran the installer, which then synced correctly.

Download new OneDrive client

Was running Office 2013 and had upgraded to 2016, then at some point my creds expired on my O365 account - from that point on it wouldn't sync ..Makes sense I guess.

If you've recently changed your Active Directory password, this error message will appear and persist until you completely exit the application (including killing any leftover processes in Task Manager) and restart it.

Upon restarting the application, it will reconnect using your new credentials and should work.

Other issues that are not related to a password change most likely require more complex steps detailed in the other answers.

close out of all microsoft programs, then open up word, go to file then account and log out of account. then log back in, then restart your computer. this should fix the issue