To troubleshoot Active Directory authentication errors, the following steps should be followed:

1. Check the username and password
   Verify that the correct username and password are being used for authentication.
2. Confirm domain name
   Ensure that the domain name is correctly entered and that the user account is a member of the domain.
3. Validate account permissions
   Determine that the user account has the appropriate permissions to access the relevant resources.
4. Verify network connection
   Ensure that a stable and reliable connection to the domain controller is present.
5. Test other user accounts
   Try authenticating with different user accounts to determine if the issue is specific to one user.
6. Check authentication server logs
   Examine the domain controller logs to determine if the account is attempting to authenticate.