Red Hat Satellite upgrade from version 5.4 to 5.6 failed with error "column "md5" of relation "rhnpackagefile" does not exist".

Issue

• After following the instructions to upgrade Red Hat Satellite server from version 5.4.1 to 5.6 it fails with the following error:

$ sudo /mnt/sat/install.pl --upgrade
* Starting the Spacewalk installer.
* Performing pre-install checks.
* Pre-install checks complete.  Beginning installation.
* RHN Registration.
** Registration: System is already registered with RHN.  Not re-registering.
[...]
** Database: Migrating data.
*** Database: Migration process logged at: /var/log/rhn/rhn_db_migration.log
*** Data migration failed.  Exit value: 3.
Please examine /var/log/rhn/rhn_installation.log for more information.

$ sudo tail -n 3 /var/log/rhn/rhn_db_migration.log
DELETE 4
psql:<stdin>:44745139: ERROR:  column "md5" of relation "rhnpackagefile" does not exist
SIGPIPE received.