This error (Error: invalid_grant Internal Error: error getting token) from Parcelhub typically occurs due to incorrect credentials on the Parcelhub connection.
To resolve this issue please review the steps below:
Check Credentials
Click Connect then Courier Integrations.
Click Parcelhub.
Click Edit against the affected connection.
Check for any spaces before or after the Username or Password that shouldn’t be there.
Verify Login
As an additional step, you can go to the Parcelhub Login Page and try to log in using the credentials on the connection to ensure they are correct.
By following these steps, you should be able to resolve the authentication error.