To resolve the Validation error:
Contact the client.
From the Login screen, check the Accountants Practice ID is correct.
In the User Name/Email Address field, ask the client to type in their Email address.
Enter the Password and click Login.
If the end user is still unable to login, raise a support case online with the following screenshots
The details the user entered on the login screen (before the error occurs).
The error that occurs.
In Practice Manager, open the Client Details window for the client, under Related, in the Document Hub field, click the ellipsis to open the Document Hub Configuration for window. Screenshot this window and attach to the case.