The refresh token must not be null nor white space
This error occurs because MigrationWiz does not have an authentication token for Google migration using user credentials. This can happen when the project type has been switched from either a Google endpoint with user credentials or a simple IMAP. Waiting a few minutes and resubmitting the migration should give the system enough time to reset and send an authentication email to the end user to perform an OAuth2 challenge. If waiting is not enough, you can:
- Select the affected user(s).
- Click on Clear Crendentials in the top navigation bar.
- Select either Clear Source credentials or Clear Destination credentials in the panel that pops up.
- Click on the Clear Credential button.
- Wait a few minutes for the migration cache to clear up. This can take up to 15 minutes.
- Resubmit your user(s) for Verify Credentials.