Red Hat Satellite upgrade to 6.4 fails with, Upstream username and password may only be set on custom repositories

Issue

• Red Hat Satellite upgrade to 6.4 fails with any of the below errors :

ActiveRecord::RecordInvalid: Validation failed: Upstream username and password may only be set on custom repositories.
ActiveRecord::RecordInvalid: Validation failed: Upstream password requires upstream username be set.

• Red Hat Satellite 6 upgrade fails at below step:

[ERROR 2018-10-29T08:49:09 main] foreman-rake katello:upgrades:3.8:clear_checksum_type failed! Check the output for error!
[ERROR 2018-10-29T08:49:09 main] Upgrade step clear_checksum_type failed. Check logs for more information.