Problem

You notice the error “Throttling limit reached, stopping migration” in the user migration logs.

Cause

As explained elsewhere, Google has its own throttling limitations which means you can only migrate between 2.5 and 3.5 GB of data within 18-24 hours per user.

Cloudiway automatically stops the migration of a user when this limit is reached.

Resolution

There is nothing to do: this is expected behavior.
The migration of a pending user is automatically restarted.