rhn-migrate-classic-to-rhsm command throws "This system appears to be already registered to Red Hat Subscription Management. Exiting."

Issue

• Running rhn-migrate-classic-to-rhsm prints the following message and I cannot migrate to RHSM:

[root@example]# rhn-migrate-classic-to-rhsm
Red Hat account: redhat
Password: 

This system appears to be already registered to Red Hat Subscription Management.  Exiting.
Please visit https://access.redhat.com/management/consumers/5992e7fd-c245-40b3-b77d-ced392b0000e to view the profile details.

• I have already deleted the system profile from the Customer Portal, accessing the above URL gives me an error.