Problem

During your mail migration from Google, you’re hitting the following error:

Google.Apis.Requests.RequestError
Access Not Configured. Tasks API has not been used in project [xxx] before or it is disabled. Enable it by visiting https://console.developers.google.com/apis/api/tasks/overview?project=[xxx] then retry. If you enabled this API recently, wait a few minutes for the action to propagate to our systems and retry. [403]

Cause

You didn’t activate the task APIs in the Google developer console.

Resolution

Connect to google developer console and activate the Task api: