Overview
AD/Windows accounts may get a seemingly generic "Authentication failed" error when trying to log in to an M-Files vault, though their access rights are correctly set and the same accounts can access other AD-based services without issues.Solution
1. Repeat the failed login attempt.
2. On the M-Files server computer, check Windows Event Viewer's Security log.
3. Look for an "Audit Failure" event with the affected user name on it.
4. Check the "Failure Reason" in the event.
If the Failure Reason is "The user has not been granted the requested logon type at this machine", then your AD environment has a Group Policy or the M-Files server has a local security policy that denies regular users the "Access this computer from the network" right. This access right is required for the users to log in to M-Files with Windows/AD accounts.
Review your Group Policies and add the "Access this computer from the network" rights to Users or Authenticated Users. In Group Policy Management Editor, this setting is under Computer Configuration > Policies > Windows Settings > Security Settings > Local Policies > User Rights Assignment, as shown below:
