[Satellite 6] Upgrading Satellite6 to 6.0.7, while enabling repositories or while accessing Products in on WebUI, it fails with:500 Internal Server Error

Issue

• Applying errata of Satellite 6.0.7 by yum update command, it fails with HTTP errors 500 or 400.
• Restart of Satellite relevant services does not help.
• After applying latest patches on the Red Hat Satellite 6, internal server error occur when trying to view products from Satellite WebUI or trying to Sync repositories results in Internal Server Error from apache.

Entries from foreman-ssl_error_ssl.log:

[Tue Jan 20 15:00:08.238479 2015] [:error] [pid 3390] [remote 10.xx.xx.xxx:244] mod_wsgi (pid=3390): Exception occurred processing WSG
[Tue Jan 20 15:00:08.238563 2015] [:error] [pid 3390] [remote 10.xx.xx.xxx:244] TypeError: 'NoneType' object is not callable

Entries from /var/log/message:

Jan 20 15:25:06 satellite.fqdn pulp: pulp.server.db.migrate.models:ERROR: pulp_rpm.plugins.migrations hasn't been updated to the latest available migration.
Jan 20 15:25:06satellite.fqdn pulp: pulp.server.webservices.application:CRITICAL: 
Jan 20 15:25:06 satellite.fqdn pulp: pulp.server.webservices.application:CRITICAL: The Pulp server failed to start due to the following reasons:
Jan 20 15:25:06 satellite.fqdn: pulp.server.webservices.application:ERROR:   The database has not been migrated to the current version. Run pulp-manage-db and restart the application.
Jan 20 15:25:06 satellite.fqdn pulp: pulp.server.webservices.application:ERROR: Traceback (most recent call last):
Jan 20 15:25:06 satellite.fqdn: pulp.server.webservices.application:ERROR:   File "/usr/lib/python2.7/site-packages/pulp/server/webservices/application.py", line 147, in wsgi_application
Jan 20 15:25:06 satellite.fqdn pulp: pulp.server.webservices.application:ERROR:     _initialize_pulp()
Jan 20 15:25:06 satellite.fqdn pulp: pulp.server.webservices.application:ERROR:   File "/usr/lib/python2.7/site-packages/pulp/server/webservices/application.py", line 102, in _initialize_pulp
Jan 20 15:25:06 satellite.fqdn pulp: pulp.server.webservices.application:ERROR:     migration_models.check_package_versions()
Jan 20 15:25:06 satellite.fqdn pulp: pulp.server.webservices.application:ERROR:   File "/usr/lib/python2.7/site-packages/pulp/server/db/migrate/models.py", line 291, in check_package_versions
Jan 20 15:25:06 satellite.fqdn pulp: pulp.server.webservices.application:ERROR:     raise Exception(error_message)
Jan 20 15:25:06 satellite.fqdn pulp: pulp.server.webservices.application:ERROR: InitializationException: The database has not been migrated to the current version. Run pulp-manage-db and restart the application.
Jan 20 15:25:06 satellite.fqdn pulp: pulp.server.webservices.application:CRITICAL:

Entries from /var/log/foreman/production.log:

Processing by Katello::Api::V2::RepositoriesController#index as JSON
 Parameters: {"enabled"=>"true", "full_result"=>"true", "library"=>"true", "organization_id"=>"4", "page"=>"1",  "product_id"=>"15", "search"=>"", "api_version"=>"v2"}
[ERROR 2015-01-20 11:20:09 pulp_rest  #10620] RestClient.get "https://satellite.fqdn/pulp/api/v2/tasks/?tag=pulp:repository:IT-Red_Hat_Enterprise_Linux_Server-Red_Hat_Enterprise_Linux_5_Server_Kickstart_x86_64_5Server&tag=pulp:action:sync", "Accept"=>"*/*; q=0.5, application/xml", "Accept-Encoding"=>"gzip, deflate", "Authorization"=>"OAuth oauth_consumer_key=\"katello\", oauth_nonce=\"OjQAmoh1gWt1sVST7jhIxv5yy3E15gYrU9LLehsqSY\", oauth_signature=\"RwSGXMbR%2BrAat1CI2xM9Ifxlcq8%3D\", oauth_signature_method=\"HMAC-SHA1\", oauth_timestamp=\"1421752809\", oauth_version=\"1.0\"", "accept"=>"application/json", "content_type"=>"application/json", "pulp-user"=>"admin-37603160" | \n# => 500 InternalServerError | text/html 531 bytes| 
[ERROR 2015-01-20 11:20:09 pulp_rest  #10620] RestClient.get "https://satellite.fqdn/pulp/api/v2/repositories/IT-Red_Hat_Enterprise_Linux_Server-Red_Hat_Enterprise_Linux_5_Server_Kickstart_x86_64_5Server//history/sync/", "Accept"=>"*/*; q=0.5, application/xml", "Accept-Encoding"=>"gzip, deflate", "Authorization"=>"OAuth oauth_consumer_key=\"katello\", oauth_nonce=\"I9TqlqF3axBEgVH62HofFcBa8SipHiWS4tqKt5Z04\", oauth_signature=\"hnWoTXfUb7lof3h1NAScmvJ7icU%3D\", oauth_signature_method=\"HMAC-SHA1\", oauth_timestamp=\"1421752809\", oauth_version=\"1.0\"", "accept"=>"application/json", "content_type"=>"application/json", "pulp-user"=>"admin-37603160" | \n# => 500 InternalServerError | text/html 531 bytes|  
Rendered /opt/rh/ruby193/root/usr/share/gems/gems/katello-1.5.0/app/views/katello/api/v2/repositories/index.json.rabl within katello/api/v2/layouts/collection (83.4ms) exception when talking to a remote client: 500 Internal Server Error 
RestClient::InternalServerError: 500 Internal Server Error