ERROR: [7496-21-5-00001D4A] Unable to login to GroupWise as user 'XXxxxxxxxx'

This is usually a problem with the trusted API. The initial setup for migration establishes a trust such that the admin account specified in the migration setup can use admin credentials to log into users' accounts to migrate mail. A special token is created and stored in the gwmigapp.ini file for use later in the migration. The token is stored as the value of the TK= parameter, in the [GroupWise] section. For example:

Since it takes time to create and propagate this information through the GroupWise system, we want to keep and re-use the token whenever we can, and this approach usually works fine once the trust is established. But if certain environmental conditions or variables should change, either in the GroupWise source or within the migration machine, the original trusted token will not work and must be re-negotiated.

The solution to the problem is to edit the INI file and remove the token. That is, simply remove the parameter value in the gwmigapp.ini file:

Then, the next program run will detect the missing token and create a new one.