1) specify a host parameter with the @ symbol, eg, a package-set, as found in the database:


> echo "select id, name, value, type from parameters" | sudo -u postgres psql -d foreman
could not change directory to "/root"
 id |        name        |        value         |      type      
----+--------------------+----------------------+-----------------
  1 | enable-epel        | false                | CommonParameter
  2 | enable-puppet5     | true                 | CommonParameter
  3 | kt_activation_keys | DEV-RHEL7-INFRA-VIRT | GroupParameter
  4 | kt_activation_keys | DEV-RHEL8-INFRA-VIRT | GroupParameter
  5 | package-set        | @Core                | GroupParameter
  7 | package-set        | @Base                | HostParameter
  8 | package-set        | @Base                | HostParameter
(7 rows)

2) Attempt to upgrade from 6.5 to 6.6

Upgrade Step: migrate_foreman...                                                                                                                  
rake aborted!                                                                                                                                     
StandardError: An error has occurred, this and all later migrations canceled:                                                                     
                                                                                                                                                  
765: unexpected token at '@Core'                                                                                                                  
/usr/share/foreman/db/migrate/20181105061336_cast_key_types_and_values_in_parameters.rb:22:in `rescue in override_key_type_and_value'

Workaround is to update these values via manual SQL from the root shell:

# echo "update parameters set value = 'FixMe' where value like '@%';" | sudo -u postgres psql -d foreman

Then perform the upgrade and correct the parameters in the UI by hand.