The installation\upgradation attempt fails with "Could not evaluate: Proxy satellite.example.com cannot be retrieved: unknown error (response 500)" error for Red Hat Satellite 6

Issue

• Executing satellite-installer --scenario satellite --upgrade runs without error until it reaches Upgrade Step: Running installer... and then it gets to 98% and throws the below error.

  Upgrade Step: Running installer...
  /Stage[main]/Foreman_proxy::Register/Foreman_smartproxy[satellite.example.com]: Could not evaluate: Proxy satellite.example.com cannot be retrieved: unknown error (response 500)
  /usr/share/foreman-installer/modules/foreman/lib/puppet/provider/foreman_smartproxy/rest_v3.rb:7:in `proxy'
  /usr/share/foreman-installer/modules/foreman/lib/puppet/provider/foreman_smartproxy/rest_v3.rb:13:in `id'
  /usr/share/foreman-installer/modules/foreman/lib/puppet/provider/foreman_smartproxy/rest_v3.rb:17:in `exists?'
  /usr/share/ruby/vendor_ruby/puppet/property/ensure.rb:81:in `retrieve'
  /usr/share/ruby/vendor_ruby/puppet/type.rb:1048:in `retrieve'
  /usr/share/ruby/vendor_ruby/puppet/type.rb:1076:in `retrieve_resource'
  /usr/share/ruby/vendor_ruby/puppet/transaction/resource_harness.rb:236:in `from_resource'
  /usr/share/ruby/vendor_ruby/puppet/transaction/resource_harness.rb:19:in `evaluate'
  

• A similar problem has been observed sometimes with a new installation of the Red Hat Satellite 6 server as well .