After upgrading to Red Hat Satellite 6.3, unable to load WebUI with error "Web application could not be started".

Issue

• After upgrading from RedHat Satellite 6.2 to 6.3, the WebUI fails to load and the below errors are seen in /var/log/httpd/error_log:

[ 2018-10-22 10:28:55.5856 1416/7f13642b4700 Pool2/Implementation.cpp:849 ]: Could not spawn process for group /usr/share/foreman#default: An error occured while starting up the preloader.
     in 'void Passenger::ApplicationPool2::SmartSpawner::handleErrorResponse(Passenger::ApplicationPool2::SmartSpawner::StartupDetails&)' (SmartSpawner.h:455)
[ 2018-10-22 10:28:55.5857 1416/7f1364d4a700 agents/HelperAgent/RequestHandler.h:1971 ]: [Client 22] Cannot checkout session. An error occured while starting up the preloader.
Error page:
undefined method `override=' for #<Filter:0x000000000688c380> (NoMethodError)

• Running the command # hammer -d ping fails with below error:

[ INFO 2018-10-23 07:16:01 HammerCLI::MainCommand] Called with options: {"option_debug"=>true}
[DEBUG 2018-10-23 07:16:01 Exception] Using exception handler HammerCLIKatello::ExceptionHandler#handle_usage_exception
[ERROR 2018-10-23 07:16:01 Exception] Error: too many arguments