Gmail Api return Unauthorized client or scope in request

Question

I have struggled to make this work but did half the job.

Actually I can only read messages from Gmail API, If I try to use the gmail.modify Scope I get an error:

Answer 1

Based from this documentation, you need to use the client ID from your "Developers Console" as the Client Name in the "Manage API client access" when you're setting your API scopes. Google API does not work as expected with your personal account @gmail.com. You should have organization domain account in Google in format you@your_organisation_domain.

Check these threads:

• Google API Python unauthorized_client: Unauthorized client or scope in request
• Google API OAuth2, Service Account, "error" : "invalid_grant"