Hi!

After installing the light version of the Q&A plugin, I recieve the following error while starting te webserver. Installation goes fine.. Any help? We also use the pro versions of CRM and Helpdesk and they're working okay.

Redmine version 4.0.4
Ruby 2.6.3p62 (2019-04-16 revision 67580) [x86_64-linux]
Rails 5.2.3
MySQL

[root@redmine redmine-4.0.4]# bundle exec rails server webrick -e production
=> Booting WEBrick
=> Rails 5.2.3 application starting in production on http://0.0.0.0:3000
=> Run `rails server -h` for more startup options
Exiting
Traceback (most recent call last):
        73: from bin/rails:4:in `<main>'
        72: from bin/rails:4:in `require'
        71: from /usr/share/gems/gems/railties-5.2.3/lib/rails/commands.rb:18:in `<top (required)>'
        70: from /usr/share/gems/gems/railties-5.2.3/lib/rails/command.rb:46:in `invoke'
        69: from /usr/share/gems/gems/railties-5.2.3/lib/rails/command/base.rb:65:in `perform'
        68: from /usr/share/gems/gems/thor-0.20.3/lib/thor.rb:387:in `dispatch'
        67: from /usr/share/gems/gems/thor-0.20.3/lib/thor/invocation.rb:126:in `invoke_command'
        66: from /usr/share/gems/gems/thor-0.20.3/lib/thor/command.rb:27:in `run'
        65: from /usr/share/gems/gems/railties-5.2.3/lib/rails/commands/server/server_command.rb:142:in `perform'
        64: from /usr/share/gems/gems/railties-5.2.3/lib/rails/commands/server/server_command.rb:142:in `tap'
        63: from /usr/share/gems/gems/railties-5.2.3/lib/rails/commands/server/server_command.rb:147:in `block in perform'
        62: from /usr/share/gems/gems/railties-5.2.3/lib/rails/commands/server/server_command.rb:53:in `start'
        61: from /usr/share/gems/gems/rack-2.0.7/lib/rack/server.rb:283:in `start'
        60: from /usr/share/gems/gems/rack-2.0.7/lib/rack/server.rb:354:in `wrapped_app'
        59: from /usr/share/gems/gems/railties-5.2.3/lib/rails/commands/server/server_command.rb:27:in `app'
        58: from /usr/share/gems/gems/rack-2.0.7/lib/rack/server.rb:219:in `app'
        57: from /usr/share/gems/gems/rack-2.0.7/lib/rack/server.rb:319:in `build_app_and_options_from_config'
        56: from /usr/share/gems/gems/rack-2.0.7/lib/rack/builder.rb:40:in `parse_file'
        55: from /usr/share/gems/gems/rack-2.0.7/lib/rack/builder.rb:49:in `new_from_string'
        54: from /usr/share/gems/gems/rack-2.0.7/lib/rack/builder.rb:49:in `eval'
        53: from config.ru:in `<main>'
        52: from config.ru:in `new'
        51: from /usr/share/gems/gems/rack-2.0.7/lib/rack/builder.rb:55:in `initialize'
        50: from /usr/share/gems/gems/rack-2.0.7/lib/rack/builder.rb:55:in `instance_eval'
        49: from config.ru:3:in `block in <main>'
        48: from /usr/share/gems/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `require'
        47: from /usr/share/gems/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:257:in `load_dependency'
        46: from /usr/share/gems/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `block in require'
        45: from /usr/share/gems/gems/polyglot-0.3.5/lib/polyglot.rb:65:in `require'
        44: from /usr/share/gems/gems/polyglot-0.3.5/lib/polyglot.rb:65:in `require'
        43: from /var/www/redmine-4.0.4/config/environment.rb:14:in `<top (required)>'
        42: from /usr/share/gems/gems/railties-5.2.3/lib/rails/application.rb:361:in `initialize!'
        41: from /usr/share/gems/gems/railties-5.2.3/lib/rails/initializable.rb:60:in `run_initializers'
        40: from /usr/share/ruby/tsort.rb:205:in `tsort_each'
        39: from /usr/share/ruby/tsort.rb:226:in `tsort_each'
        38: from /usr/share/ruby/tsort.rb:347:in `each_strongly_connected_component'
        37: from /usr/share/ruby/tsort.rb:347:in `call'
        36: from /usr/share/ruby/tsort.rb:347:in `each'
        35: from /usr/share/ruby/tsort.rb:349:in `block in each_strongly_connected_component'
        34: from /usr/share/ruby/tsort.rb:431:in `each_strongly_connected_component_from'
        33: from /usr/share/ruby/tsort.rb:350:in `block (2 levels) in each_strongly_connected_component'
        32: from /usr/share/ruby/tsort.rb:228:in `block in tsort_each'
        31: from /usr/share/gems/gems/railties-5.2.3/lib/rails/initializable.rb:61:in `block in run_initializers'
        30: from /usr/share/gems/gems/railties-5.2.3/lib/rails/initializable.rb:32:in `run'
        29: from /usr/share/gems/gems/railties-5.2.3/lib/rails/initializable.rb:32:in `instance_exec'
        28: from /usr/share/gems/gems/railties-5.2.3/lib/rails/application/finisher.rb:69:in `block in <module:Finisher>'
        27: from /usr/share/gems/gems/railties-5.2.3/lib/rails/application/finisher.rb:69:in `each'
        26: from /usr/share/gems/gems/railties-5.2.3/lib/rails/engine.rb:356:in `eager_load!'
        25: from /usr/share/gems/gems/railties-5.2.3/lib/rails/engine.rb:475:in `eager_load!'
        24: from /usr/share/gems/gems/railties-5.2.3/lib/rails/engine.rb:475:in `each'
        23: from /usr/share/gems/gems/railties-5.2.3/lib/rails/engine.rb:477:in `block in eager_load!'
        22: from /usr/share/gems/gems/railties-5.2.3/lib/rails/engine.rb:477:in `each'
        21: from /usr/share/gems/gems/railties-5.2.3/lib/rails/engine.rb:478:in `block (2 levels) in eager_load!'
        20: from /usr/share/gems/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:246:in `require_dependency'
        19: from /usr/share/gems/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:334:in `depend_on'
        18: from /usr/share/gems/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:356:in `require_or_load'
        17: from /usr/share/gems/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:37:in `load_interlock'
        16: from /usr/share/gems/gems/activesupport-5.2.3/lib/active_support/dependencies/interlock.rb:13:in `loading'
        15: from /usr/share/gems/gems/activesupport-5.2.3/lib/active_support/concurrency/share_lock.rb:151:in `exclusive'
        14: from /usr/share/gems/gems/activesupport-5.2.3/lib/active_support/dependencies/interlock.rb:14:in `block in loading'
        13: from /usr/share/gems/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:37:in `block in load_interlock'
        12: from /usr/share/gems/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:378:in `block in require_or_load'
        11: from /usr/share/gems/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `require'
        10: from /usr/share/gems/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:257:in `load_dependency'
         9: from /usr/share/gems/gems/activesupport-5.2.3/lib/active_support/dependencies.rb:291:in `block in require'
         8: from /usr/share/gems/gems/polyglot-0.3.5/lib/polyglot.rb:65:in `require'
         7: from /usr/share/gems/gems/polyglot-0.3.5/lib/polyglot.rb:65:in `require'
         6: from /var/www/redmine-4.0.4/plugins/redmine_questions/lib/redmine_questions/patches/compatibility/application_controller_patch.rb:36:in `<top (required)>'
         5: from /var/www/redmine-4.0.4/plugins/redmine_questions/lib/redmine_questions/patches/compatibility/application_controller_patch.rb:36:in `include'
         4: from /var/www/redmine-4.0.4/plugins/redmine_questions/lib/redmine_questions/patches/compatibility/application_controller_patch.rb:24:in `included'
         3: from /var/www/redmine-4.0.4/plugins/redmine_questions/lib/redmine_questions/patches/compatibility/application_controller_patch.rb:24:in `class_eval'
         2: from /var/www/redmine-4.0.4/plugins/redmine_questions/lib/redmine_questions/patches/compatibility/application_controller_patch.rb:26:in `block in included'
         1: from /var/www/redmine-4.0.4/plugins/redmine_questions/lib/redmine_questions/patches/compatibility/application_controller_patch.rb:27:in `singleton class'
/var/www/redmine-4.0.4/plugins/redmine_questions/lib/redmine_questions/patches/compatibility/application_controller_patch.rb:27:in `alias_method': undefined method `before_filter' for class `#<Class:ApplicationController>' (NameError)