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

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.

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

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

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\

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.