Gmail Trigger node common issues

Here are some common errors and issues with the Gmail Trigger node and steps to resolve or troubleshoot them.

401 unauthorized error

The full text of the error looks like this:

401 - {"error":"unauthorized_client","error_description":"Client is unauthorized to retrieve access tokens using this method, or client not authorized for any of the scopes requested."}

This error occurs when there's an issue with the credential you're using and its scopes or permissions.

To resolve:

1. For OAuth2 credentials, make sure you've enabled the Gmail API in APIs & Services > Library. Refer to Google OAuth2 Single Service - Enable APIs for more information.
2. For Service Account credentials:
   1. Enable domain-wide delegation.
   2. Make sure you add the Gmail API as part of the domain-wide delegation configuration.