When I try to assign/unassign an LDAP user to an LDAP group, Foreman throws this segfault:

NoMethodError
undefined method `[]=' for #<ActiveModel::Errors:0x00007f1cebd76478> Did you mean? []
/usr/share/foreman/app/controllers/usergroups_controller.rb:40:in `rescue in update'
/usr/share/foreman/app/controllers/usergroups_controller.rb:32:in `update'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_controller/metal/basic_implicit_render.rb:6:in `send_action'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/abstract_controller/base.rb:194:in `process_action'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_controller/metal/rendering.rb:30:in `process_action'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/abstract_controller/callbacks.rb:42:in `block in process_action'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/activesupport-5.2.1/lib/active_support/callbacks.rb:109:in `block in run_callbacks'
/usr/share/foreman/app/controllers/concerns/application_shared.rb:15:in `set_timezone'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/activesupport-5.2.1/lib/active_support/callbacks.rb:118:in `block in run_callbacks'
/usr/share/foreman/app/models/concerns/foreman/thread_session.rb:32:in `clear_thread'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/activesupport-5.2.1/lib/active_support/callbacks.rb:118:in `block in run_callbacks'
/usr/share/foreman/app/controllers/concerns/foreman/controller/topbar_sweeper.rb:12:in `set_topbar_sweeper_controller'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/activesupport-5.2.1/lib/active_support/callbacks.rb:118:in `block in run_callbacks'
/opt/theforeman/tfm/root/usr/share/gems/gems/audited-4.7.1/lib/audited/sweeper.rb:14:in `around'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/activesupport-5.2.1/lib/active_support/callbacks.rb:118:in `block in run_callbacks'
/opt/theforeman/tfm/root/usr/share/gems/gems/audited-4.7.1/lib/audited/sweeper.rb:14:in `around'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/activesupport-5.2.1/lib/active_support/callbacks.rb:118:in `block in run_callbacks'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/activesupport-5.2.1/lib/active_support/callbacks.rb:136:in `run_callbacks'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/abstract_controller/callbacks.rb:41:in `process_action'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_controller/metal/rescue.rb:22:in `process_action'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_controller/metal/instrumentation.rb:34:in `block in process_action'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/activesupport-5.2.1/lib/active_support/notifications.rb:168:in `block in instrument'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/activesupport-5.2.1/lib/active_support/notifications/instrumenter.rb:23:in `instrument'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/activesupport-5.2.1/lib/active_support/notifications.rb:168:in `instrument'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_controller/metal/instrumentation.rb:32:in `process_action'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_controller/metal/params_wrapper.rb:256:in `process_action'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/activerecord-5.2.1/lib/active_record/railties/controller_runtime.rb:24:in `process_action'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/abstract_controller/base.rb:134:in `process'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionview-5.2.1/lib/action_view/rendering.rb:32:in `process'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_controller/metal.rb:191:in `dispatch'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_controller/metal.rb:252:in `dispatch'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_dispatch/routing/route_set.rb:52:in `dispatch'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_dispatch/routing/route_set.rb:34:in `serve'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_dispatch/journey/router.rb:52:in `block in serve'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_dispatch/journey/router.rb:35:in `each'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_dispatch/journey/router.rb:35:in `serve'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_dispatch/routing/route_set.rb:840:in `call'
/opt/theforeman/tfm/root/usr/share/gems/gems/apipie-rails-0.5.14/lib/apipie/static_dispatcher.rb:65:in `call'
/opt/theforeman/tfm/root/usr/share/gems/gems/apipie-rails-0.5.14/lib/apipie/extractor/recorder.rb:137:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_dispatch/middleware/static.rb:127:in `call'
/usr/share/foreman/lib/foreman/middleware/telemetry.rb:10:in `call'
/opt/theforeman/tfm/root/usr/share/gems/gems/apipie-rails-0.5.14/lib/apipie/middleware/checksum_in_headers.rb:27:in `call'
/usr/share/foreman/lib/foreman/middleware/catch_json_parse_errors.rb:9:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/rack-2.0.5/lib/rack/tempfile_reaper.rb:15:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/rack-2.0.5/lib/rack/etag.rb:25:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/rack-2.0.5/lib/rack/conditional_get.rb:38:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/rack-2.0.5/lib/rack/head.rb:12:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_dispatch/http/content_security_policy.rb:18:in `call'
/usr/share/foreman/lib/foreman/middleware/logging_context_session.rb:22:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/rack-2.0.5/lib/rack/session/abstract/id.rb:232:in `context'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/rack-2.0.5/lib/rack/session/abstract/id.rb:226:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_dispatch/middleware/cookies.rb:670:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/activesupport-5.2.1/lib/active_support/callbacks.rb:98:in `run_callbacks'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_dispatch/middleware/callbacks.rb:26:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_dispatch/middleware/debug_exceptions.rb:61:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_dispatch/middleware/show_exceptions.rb:33:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/railties-5.2.1/lib/rails/rack/logger.rb:38:in `call_app'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/railties-5.2.1/lib/rails/rack/logger.rb:28:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/sprockets-rails-3.2.1/lib/sprockets/rails/quiet_assets.rb:13:in `call'
/usr/share/foreman/lib/foreman/middleware/logging_context_request.rb:11:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_dispatch/middleware/remote_ip.rb:81:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_dispatch/middleware/request_id.rb:27:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/rack-2.0.5/lib/rack/method_override.rb:22:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/rack-2.0.5/lib/rack/runtime.rb:22:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/activesupport-5.2.1/lib/active_support/cache/strategy/local_cache_middleware.rb:29:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_dispatch/middleware/executor.rb:14:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/actionpack-5.2.1/lib/action_dispatch/middleware/static.rb:127:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/rack-2.0.5/lib/rack/sendfile.rb:111:in `call'
/opt/theforeman/tfm/root/usr/share/gems/gems/secure_headers-6.0.0/lib/secure_headers/middleware.rb:13:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/railties-5.2.1/lib/rails/engine.rb:524:in `call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/railties-5.2.1/lib/rails/railtie.rb:190:in `public_send'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/railties-5.2.1/lib/rails/railtie.rb:190:in `method_missing'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/rack-2.0.5/lib/rack/urlmap.rb:68:in `block in call'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/rack-2.0.5/lib/rack/urlmap.rb:53:in `each'
/opt/theforeman/tfm-ror52/root/usr/share/gems/gems/rack-2.0.5/lib/rack/urlmap.rb:53:in `call'
/usr/share/passenger/phusion_passenger/rack/thread_handler_extension.rb:74:in `process_request'
/usr/share/passenger/phusion_passenger/request_handler/thread_handler.rb:141:in `accept_and_process_next_request'
/usr/share/passenger/phusion_passenger/request_handler/thread_handler.rb:109:in `main_loop'
/usr/share/passenger/phusion_passenger/request_handler.rb:455:in `block (3 levels) in start_threads'
/opt/theforeman/tfm/root/usr/share/gems/gems/logging-2.2.2/lib/logging/diagnostic_context.rb:474:in `block in create_with_logging_context'

For assigning the user, even with the stack trace, the assignment works. For removing, not.