Problem solved. 

Under Setings / Vault Settings / Synchronize, I selected Disconnect.  Then I restarted Enpass, went to Settings / Vault Settings / Synchronize, and re-selected Google Drive.  Then I had to authorize my Google account to Allow Enpass, and then the Synch to Google Drive worked.

Having a problem Syncing to Google Drive using Enpass version 6.1.2 (432) on Windows 10 (version 1903).

The error message is:  Something went wrong while syncing with Google Drive.  Error code 404401

I can access Google Drive from my computer.  I also can successfully sync with Google Drive using my Android phone.

Thanks, +Hemant, that information is very helpful!

I'm also experiencing this problem with Enpass Chrome extension and the Vivaldi browser (1.0.435.52).  I do have the Enpass 5.0.5 deskop client installed and working fine, on Windows 10.  The error I receive in Vivivaldi when clicking on the Enpass extension is:

Error 403 Access Denied/Forbidden

Browser's code signature could not be verfied. Filling and other features are disabled until this configuration issue is resolved.