While it's possible through webui, the straightforward global parameter creation with hammer results in 500 Server Error.

Seen on fresh deployment from 24\10\19 (3b202fa177a8db80decc7ea40745817ed1265ad8) where fix for https://projects.theforeman.org/issues/27740 is present. Can provide an env if necessary.

hammer global-parameter set --name aaa --value aaa

Results in

[32m2019-10-24T12:13:50ESC[0m [D|ESC[36mappESC[0m|cc128e9b] Backtrace for 'Action failed' error (ActiveModel::UnknownAttributeError): unknown attribute 'location_id' for CommonParameter.
 | /home/centos/.rvm/gems/ruby-2.6.3/gems/activemodel-5.2.1/lib/active_model/attribute_assignment.rb:53:in `_assign_attribute'
 | /home/centos/.rvm/gems/ruby-2.6.3/gems/activemodel-5.2.1/lib/active_model/attribute_assignment.rb:44:in `block in _assign_attributes'
 | /home/centos/.rvm/gems/ruby-2.6.3/gems/activemodel-5.2.1/lib/active_model/attribute_assignment.rb:43:in `each'
 | /home/centos/.rvm/gems/ruby-2.6.3/gems/activemodel-5.2.1/lib/active_model/attribute_assignment.rb:43:in `_assign_attributes'
 | /home/centos/.rvm/gems/ruby-2.6.3/gems/activerecord-5.2.1/lib/active_record/attribute_assignment.rb:23:in `_assign_attributes'
 | /home/centos/.rvm/gems/ruby-2.6.3/gems/activemodel-5.2.1/lib/active_model/attribute_assignment.rb:35:in `assign_attributes'
 | /home/centos/.rvm/gems/ruby-2.6.3/gems/activerecord-5.2.1/lib/active_record/core.rb:314:in `initialize'