Here is also the production.log section

2023-10-14T08:18:46 [I|app|31b28ac4] Started GET "/notification_recipients" for 10.26.238.33 at 2023-10-14 08:18:46 +0200
2023-10-14T08:18:46 [I|app|31b28ac4] Processing by NotificationRecipientsController#index as JSON
2023-10-14T08:18:46 [I|app|31b28ac4] Completed 200 OK in 6ms (Views: 0.1ms | ActiveRecord: 1.0ms | Allocations: 1948)
2023-10-14T08:18:47 [I|app|7b0f6338] Started GET "/new/hosts/#####################" for 10.26.238.33 at 2023-10-14 08:18:47 +0200
2023-10-14T08:18:47 [I|app|7b0f6338] Processing by ReactController#index as HTML
2023-10-14T08:18:47 [I|app|7b0f6338] Parameters: {"id"=>"###########################"}
2023-10-14T08:18:47 [I|app|7b0f6338] Rendered react/index.html.erb within layouts/react_application (Duration: 0.0ms | Allocations: 4)
2023-10-14T08:18:47 [I|app|7b0f6338] Rendered layouts/base.html.erb (Duration: 16.1ms | Allocations: 13018)
2023-10-14T08:18:47 [I|app|7b0f6338] Rendered layout layouts/react_application.html.erb (Duration: 16.6ms | Allocations: 13167)
2023-10-14T08:18:47 [I|app|7b0f6338] Completed 200 OK in 27ms (Views: 16.2ms | ActiveRecord: 3.0ms | Allocations: 15908)
2023-10-14T08:18:47 [I|app|ea0b7781] Started GET "/notification_recipients" for 10.26.238.33 at 2023-10-14 08:18:47 +0200
2023-10-14T08:18:47 [I|app|b141e7fe] Started GET "/api/hosts/######################m?show_hidden_parameters=true" for 10.26.238.33 at 2023-10-14 08:18:47 +0200
2023-10-14T08:18:47 [I|app|b141e7fe] Processing by Api::V2::HostsController#show as JSON
2023-10-14T08:18:47 [I|app|b141e7fe] Parameters: {"show_hidden_parameters"=>"true", "apiv"=>"v2", "id"=>"ot#########################"}
2023-10-14T08:18:47 [I|app|ea0b7781] Processing by NotificationRecipientsController#index as JSON
2023-10-14T08:18:47 [I|app|ea0b7781] Completed 200 OK in 14ms (Views: 0.1ms | ActiveRecord: 4.1ms | Allocations: 4756)
2023-10-14T08:18:47 [I|app|b141e7fe] Rendered api/v2/hosts/show.json.rabl (Duration: 76.7ms | Allocations: 23583)
2023-10-14T08:18:47 [I|app|b141e7fe] Completed 200 OK in 100ms (Views: 64.7ms | ActiveRecord: 22.5ms | Allocations: 31509)
2023-10-14T08:18:47 [I|app|78448d0d] Started GET "/hosts/#########################/statuses" for 10.26.238.33 at 2023-10-14 08:18:47 +0200
2023-10-14T08:18:47 [I|app|7ec2b8fd] Started GET "/api/audits?search=host%3D##################&per_page=3" for 10.26.238.33 at 2023-10-14 08:18:47 +0200
2023-10-14T08:18:47 [I|app|c84b623e] Started GET "/api/hosts/######################/power?timeout=30" for 10.26.238.33 at 2023-10-14 08:18:47 +0200
2023-10-14T08:18:47 [I|app|78448d0d] Processing by HostsController#statuses as JSON
2023-10-14T08:18:47 [I|app|78448d0d] Parameters: {"id"=>"#######################"}
2023-10-14T08:18:47 [I|app|7ec2b8fd] Processing by Api::V2::AuditsController#index as JSON
2023-10-14T08:18:47 [I|app|7ec2b8fd] Parameters: {"search"=>"host=#################", "per_page"=>"3", "apiv"=>"v2"}
2023-10-14T08:18:47 [I|app|c84b623e] Processing by Api::V2::HostsController#power_status as JSON
2023-10-14T08:18:47 [I|app|c84b623e] Parameters: {"timeout"=>"30", "apiv"=>"v2", "id"=>"###########################"}
2023-10-14T08:18:47 [I|app|78448d0d] Completed 200 OK in 22ms (Views: 0.3ms | ActiveRecord: 3.5ms | Allocations: 5246)
2023-10-14T08:18:47 [I|app|c84b623e] Completed 200 OK in 20ms (Views: 0.2ms | ActiveRecord: 8.8ms | Allocations: 6080)
2023-10-14T08:18:48 [I|app|7ec2b8fd] Rendered api/v2/audits/index.json.rabl within api/v2/layouts/index_layout (Duration: 41.1ms | Allocations: 14281)
2023-10-14T08:18:48 [I|app|7ec2b8fd] Rendered layout api/v2/layouts/index_layout.json.erb (Duration: 46.2ms | Allocations: 15664)
2023-10-14T08:18:48 [I|app|7ec2b8fd] Completed 200 OK in 57ms (Views: 41.1ms | ActiveRecord: 8.0ms | Allocations: 18311)
2023-10-14T08:18:49 [I|app|e47aece6] Started GET "/disks/bootdisk_options/13" for 10.26.238.33 at 2023-10-14 08:18:49 +0200
2023-10-14T08:18:49 [I|app|e47aece6] Processing by ForemanBootdisk::DisksController#bootdisk_options as JSON
2023-10-14T08:18:49 [I|app|e47aece6] Parameters: {"id"=>"13"}
2023-10-14T08:18:49 [I|app|e47aece6] Completed 200 OK in 16ms (Views: 0.3ms | ActiveRecord: 3.3ms | Allocations: 4170)
2023-10-14T08:18:50 [I|app|c7db7361] Started GET "/disks/full_hosts/13" for 10.26.238.33 at 2023-10-14 08:18:50 +0200
2023-10-14T08:18:50 [I|app|c7db7361] Processing by ForemanBootdisk::DisksController#full_host as HTML
2023-10-14T08:18:50 [I|app|c7db7361] Parameters: {"id"=>"13"}
2023-10-14T08:18:50 [W|app|c7db7361] undefined method `include?' for nil:NilClass
2023-10-14T08:18:50 [I|app|c7db7361] Backtrace for 'undefined method `include?' for nil:NilClass' error (NoMethodError): undefined method `include?' for nil:NilClass
c7db7361 | /usr/share/foreman/app/models/host/managed.rb:735:in `pxe_loader_efi?'
c7db7361 | /usr/share/gems/gems/safemode-1.3.7/lib/safemode/jail.rb:31:in `method_missing'
c7db7361 | WL-RHEL-8 Kickstart default PXEGrub2 clone:57:in `bind'
c7db7361 | /usr/share/gems/gems/safemode-1.3.7/lib/safemode.rb:51:in `eval'
c7db7361 | /usr/share/gems/gems/safemode-1.3.7/lib/safemode.rb:51:in `eval'
c7db7361 | /usr/share/foreman/app/services/foreman/renderer/safe_mode_renderer.rb:7:in `render'
c7db7361 | /usr/share/foreman/app/services/foreman/renderer/base_renderer.rb:18:in `render'
c7db7361 | /usr/share/foreman/app/services/foreman/renderer.rb:46:in `render'
c7db7361 | /usr/share/gems/gems/foreman_bootdisk-21.0.4/app/services/foreman_bootdisk/renderer.rb:16:in `render_template'
c7db7361 | /usr/share/gems/gems/foreman_bootdisk-21.0.4/app/services/foreman_bootdisk/iso_generator.rb:44:in `render_template'
c7db7361 | /usr/share/gems/gems/foreman_bootdisk-21.0.4/app/services/foreman_bootdisk/iso_generator.rb:19:in `generate_full_host'
c7db7361 | /usr/share/gems/gems/foreman_bootdisk-21.0.4/app/controllers/foreman_bootdisk/disks_controller.rb:58:in `full_host'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_controller/metal/basic_implicit_render.rb:6:in `send_action'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/abstract_controller/base.rb:228:in `process_action'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_controller/metal/rendering.rb:30:in `process_action'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/abstract_controller/callbacks.rb:42:in `block in process_action'
c7db7361 | /usr/share/gems/gems/activesupport-6.1.7.3/lib/active_support/callbacks.rb:117:in `block in run_callbacks'
c7db7361 | /usr/share/foreman/app/controllers/concerns/foreman/controller/timezone.rb:10:in `set_timezone'
c7db7361 | /usr/share/gems/gems/activesupport-6.1.7.3/lib/active_support/callbacks.rb:126:in `block in run_callbacks'
c7db7361 | /usr/share/foreman/app/models/concerns/foreman/thread_session.rb:32:in `clear_thread'
c7db7361 | /usr/share/gems/gems/activesupport-6.1.7.3/lib/active_support/callbacks.rb:126:in `block in run_callbacks'
c7db7361 | /usr/share/foreman/app/controllers/concerns/foreman/controller/topbar_sweeper.rb:12:in `set_topbar_sweeper_controller'
c7db7361 | /usr/share/gems/gems/activesupport-6.1.7.3/lib/active_support/callbacks.rb:126:in `block in run_callbacks'
c7db7361 | /usr/share/gems/gems/audited-5.3.3/lib/audited/sweeper.rb:16:in `around'
c7db7361 | /usr/share/gems/gems/activesupport-6.1.7.3/lib/active_support/callbacks.rb:126:in `block in run_callbacks'
c7db7361 | /usr/share/gems/gems/audited-5.3.3/lib/audited/sweeper.rb:16:in `around'
c7db7361 | /usr/share/gems/gems/activesupport-6.1.7.3/lib/active_support/callbacks.rb:126:in `block in run_callbacks'
c7db7361 | /usr/share/gems/gems/activesupport-6.1.7.3/lib/active_support/callbacks.rb:137:in `run_callbacks'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/abstract_controller/callbacks.rb:41:in `process_action'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_controller/metal/rescue.rb:22:in `process_action'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_controller/metal/instrumentation.rb:34:in `block in process_action'
c7db7361 | /usr/share/gems/gems/activesupport-6.1.7.3/lib/active_support/notifications.rb:203:in `block in instrument'
c7db7361 | /usr/share/gems/gems/activesupport-6.1.7.3/lib/active_support/notifications/instrumenter.rb:24:in `instrument'
c7db7361 | /usr/share/gems/gems/activesupport-6.1.7.3/lib/active_support/notifications.rb:203:in `instrument'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_controller/metal/instrumentation.rb:33:in `process_action'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_controller/metal/params_wrapper.rb:249:in `process_action'
c7db7361 | /usr/share/gems/gems/activerecord-6.1.7.3/lib/active_record/railties/controller_runtime.rb:27:in `process_action'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/abstract_controller/base.rb:165:in `process'
c7db7361 | /usr/share/gems/gems/actionview-6.1.7.3/lib/action_view/rendering.rb:39:in `process'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_controller/metal.rb:190:in `dispatch'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_controller/metal.rb:254:in `dispatch'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/routing/route_set.rb:50:in `dispatch'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/routing/route_set.rb:33:in `serve'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/journey/router.rb:50:in `block in serve'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/journey/router.rb:32:in `each'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/journey/router.rb:32:in `serve'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/routing/route_set.rb:842:in `call'
c7db7361 | /usr/share/gems/gems/railties-6.1.7.3/lib/rails/engine.rb:539:in `call'
c7db7361 | /usr/share/gems/gems/railties-6.1.7.3/lib/rails/railtie.rb:207:in `public_send'
c7db7361 | /usr/share/gems/gems/railties-6.1.7.3/lib/rails/railtie.rb:207:in `method_missing'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/routing/mapper.rb:20:in `block in <class:Constraints>'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/routing/mapper.rb:49:in `serve'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/journey/router.rb:50:in `block in serve'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/journey/router.rb:32:in `each'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/journey/router.rb:32:in `serve'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/routing/route_set.rb:842:in `call'
c7db7361 | /usr/share/gems/gems/apipie-dsl-2.5.0/lib/apipie_dsl/static_dispatcher.rb:67:in `call'
c7db7361 | /usr/share/gems/gems/apipie-rails-1.1.0/lib/apipie/static_dispatcher.rb:68:in `call'
c7db7361 | /usr/share/gems/gems/apipie-rails-1.1.0/lib/apipie/extractor/recorder.rb:139:in `call'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/middleware/static.rb:24:in `call'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/middleware/static.rb:24:in `call'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/middleware/static.rb:24:in `call'
c7db7361 | /usr/share/foreman/lib/foreman/middleware/libvirt_connection_cleaner.rb:9:in `call'
c7db7361 | /usr/share/foreman/lib/foreman/middleware/telemetry.rb:10:in `call'
c7db7361 | /usr/share/gems/gems/apipie-rails-1.1.0/lib/apipie/middleware/checksum_in_headers.rb:27:in `call'
c7db7361 | /usr/share/gems/gems/rack-2.2.7/lib/rack/tempfile_reaper.rb:15:in `call'
c7db7361 | /usr/share/gems/gems/rack-2.2.7/lib/rack/etag.rb:27:in `call'
c7db7361 | /usr/share/gems/gems/rack-2.2.7/lib/rack/conditional_get.rb:27:in `call'
c7db7361 | /usr/share/gems/gems/rack-2.2.7/lib/rack/head.rb:12:in `call'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/http/permissions_policy.rb:22:in `call'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/http/content_security_policy.rb:19:in `call'
c7db7361 | /usr/share/foreman/lib/foreman/middleware/logging_context_session.rb:22:in `call'
c7db7361 | /usr/share/gems/gems/rack-2.2.7/lib/rack/session/abstract/id.rb:266:in `context'
c7db7361 | /usr/share/gems/gems/rack-2.2.7/lib/rack/session/abstract/id.rb:260:in `call'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/middleware/cookies.rb:697:in `call'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/middleware/callbacks.rb:27:in `block in call'
c7db7361 | /usr/share/gems/gems/activesupport-6.1.7.3/lib/active_support/callbacks.rb:98:in `run_callbacks'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/middleware/callbacks.rb:26:in `call'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/middleware/actionable_exceptions.rb:18:in `call'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/middleware/debug_exceptions.rb:29:in `call'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/middleware/show_exceptions.rb:33:in `call'
c7db7361 | /usr/share/gems/gems/railties-6.1.7.3/lib/rails/rack/logger.rb:37:in `call_app'
c7db7361 | /usr/share/gems/gems/railties-6.1.7.3/lib/rails/rack/logger.rb:28:in `call'
c7db7361 | /usr/share/gems/gems/sprockets-rails-3.4.2/lib/sprockets/rails/quiet_assets.rb:13:in `call'
c7db7361 | /usr/share/foreman/lib/foreman/middleware/logging_context_request.rb:11:in `call'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/middleware/remote_ip.rb:81:in `call'
c7db7361 | /usr/share/gems/gems/request_store-1.5.1/lib/request_store/middleware.rb:19:in `call'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/middleware/request_id.rb:26:in `call'
c7db7361 | /usr/share/gems/gems/rack-2.2.7/lib/rack/method_override.rb:24:in `call'
c7db7361 | /usr/share/gems/gems/rack-2.2.7/lib/rack/runtime.rb:22:in `call'
c7db7361 | /usr/share/gems/gems/activesupport-6.1.7.3/lib/active_support/cache/strategy/local_cache_middleware.rb:29:in `call'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/middleware/executor.rb:14:in `call'
c7db7361 | /usr/share/gems/gems/rack-2.2.7/lib/rack/sendfile.rb:110:in `call'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/middleware/ssl.rb:77:in `call'
c7db7361 | /usr/share/gems/gems/actionpack-6.1.7.3/lib/action_dispatch/middleware/host_authorization.rb:142:in `call'
c7db7361 | /usr/share/gems/gems/secure_headers-6.5.0/lib/secure_headers/middleware.rb:11:in `call'
c7db7361 | /usr/share/gems/gems/railties-6.1.7.3/lib/rails/engine.rb:539:in `call'
c7db7361 | /usr/share/gems/gems/railties-6.1.7.3/lib/rails/railtie.rb:207:in `public_send'
c7db7361 | /usr/share/gems/gems/railties-6.1.7.3/lib/rails/railtie.rb:207:in `method_missing'
c7db7361 | /usr/share/gems/gems/rack-2.2.7/lib/rack/urlmap.rb:74:in `block in call'
c7db7361 | /usr/share/gems/gems/rack-2.2.7/lib/rack/urlmap.rb:58:in `each'
c7db7361 | /usr/share/gems/gems/rack-2.2.7/lib/rack/urlmap.rb:58:in `call'
c7db7361 | /usr/share/gems/gems/puma-6.2.2/lib/puma/configuration.rb:270:in `call'
c7db7361 | /usr/share/gems/gems/puma-6.2.2/lib/puma/request.rb:98:in `block in handle_request'
c7db7361 | /usr/share/gems/gems/puma-6.2.2/lib/puma/thread_pool.rb:340:in `with_force_shutdown'
c7db7361 | /usr/share/gems/gems/puma-6.2.2/lib/puma/request.rb:97:in `handle_request'
c7db7361 | /usr/share/gems/gems/puma-6.2.2/lib/puma/server.rb:431:in `process_client'
c7db7361 | /usr/share/gems/gems/puma-6.2.2/lib/puma/server.rb:233:in `block in run'
c7db7361 | /usr/share/gems/gems/puma-6.2.2/lib/puma/thread_pool.rb:147:in `block in spawn_thread'
c7db7361 | /usr/share/gems/gems/logging-2.3.1/lib/logging/diagnostic_context.rb:474:in `block in create_with_logging_context'
2023-10-14T08:18:50 [I|app|c7db7361] Rendered common/500.html.erb within layouts/application (Duration: 1.3ms | Allocations: 457)
2023-10-14T08:18:50 [I|app|c7db7361] Rendered layouts/base.html.erb (Duration: 13.7ms | Allocations: 1758)
2023-10-14T08:18:50 [I|app|c7db7361] Rendered layout layouts/application.html.erb (Duration: 15.6ms | Allocations: 2422)
2023-10-14T08:18:50 [I|app|c7db7361] Completed 500 Internal Server Error in 196ms (Views: 16.2ms | ActiveRecord: 20.5ms | Allocations: 90395)

This error occurs when PXE loader field is not filled

There is a PR for it: https://github.com/theforeman/foreman/pull/9785