Problem

During migration or audit from G Suite, you have noticed the following error:
“Error:”unauthorized_client”, Description:”Client is unauthorized to retrieve access tokens using this method.”, Uri:”

Cause

The service account configured in the Google Console doesn’t have enough permissions to perform a migration or audit.

Resolution

Check if service account is configured correctly and contain all necessary scopes.
Also refer to the article ‘How to create an admin for G Suite migration’ .