**steps to reproduce:

host update --build=f --id 84692

the following is observed in the logs

2017-04-05T13:46:03 a1c5a7ea [app] [I] Started PUT "/api/hosts/84692" for 10.16.196.92 at 2017-04-05 13:46:03 +0100
2017-04-05T13:46:03 a1c5a7ea [app] [I] Processing by Api::V2::HostsController#update as JSON
2017-04-05T13:46:03 a1c5a7ea [app] [I]   Parameters: {"host"=>{"build"=>false, "compute_attributes"=>{"volumes_attributes"=>{}}, "host_parameters_attributes"=>{}, "interfaces_attributes"=>{}}, "apiv"=>"v2", "id"=>"84692"}
2017-04-05T13:46:03 a1c5a7ea [app] [I] Current user: foreman_admin (administrator)
2017-04-05T13:46:03 a1c5a7ea [app] [I] Current user: foreman_admin (administrator)
2017-04-05T13:46:03 a1c5a7ea [app] [I] Current user: admin (administrator)
2017-04-05T13:46:03 a1c5a7ea [app] [I] Authorized user admin(Ohad Levy)
2017-04-05T13:46:03 a1c5a7ea [app] [I] Current user: admin (administrator)
2017-04-05T13:46:03 a1c5a7ea [app] [W] Action failed
 | NoMethodError: undefined method `map!' for {}:ActionController::Parameters
 | /home/foreman/git/foreman/app/controllers/concerns/parameter_attributes.rb:35:in `process_update'
 | /home/foreman/git/foreman/app/controllers/concerns/parameter_attributes.rb:12:in `process_parameter_attributes'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:432:in `block in make_lambda'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:145:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:145:in `block in halting_and_conditional'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:504:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:504:in `block in call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:504:in `each'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:504:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:498:in `block (2 levels) in around'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:313:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:313:in `block (2 levels) in halting'
 | /home/foreman/git/foreman/app/controllers/api/v2/base_controller.rb:152:in `disable_json_root'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:432:in `block in make_lambda'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:312:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:312:in `block in halting'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:497:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:497:in `block in around'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:505:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:505:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:498:in `block (2 levels) in around'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:313:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:313:in `block (2 levels) in halting'
 | /home/foreman/git/foreman/app/controllers/concerns/application_shared.rb:15:in `set_timezone'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:432:in `block in make_lambda'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:312:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:312:in `block in halting'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:497:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:497:in `block in around'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:505:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:505:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:498:in `block (2 levels) in around'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:313:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:313:in `block (2 levels) in halting'
 | /home/foreman/git/foreman/app/models/concerns/foreman/thread_session.rb:32:in `clear_thread'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:432:in `block in make_lambda'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:312:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:312:in `block in halting'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:497:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:497:in `block in around'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:505:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:505:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:498:in `block (2 levels) in around'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:313:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:313:in `block (2 levels) in halting'
 | /home/foreman/git/foreman/app/controllers/concerns/foreman/controller/topbar_sweeper.rb:12:in `set_topbar_sweeper_controller'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:432:in `block in make_lambda'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:312:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:312:in `block in halting'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:497:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:497:in `block in around'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:505:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:505:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:498:in `block (2 levels) in around'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:313:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:313:in `block (2 levels) in halting'
 | /home/foreman/gems/gems/audited-4.4.1/lib/audited/sweeper.rb:14:in `around'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:455:in `public_send'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:455:in `block in make_lambda'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:312:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:312:in `block in halting'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:497:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:497:in `block in around'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:505:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:505:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:92:in `__run_callbacks__'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:778:in `_run_process_action_callbacks'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:81:in `run_callbacks'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/abstract_controller/callbacks.rb:19:in `process_action'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_controller/metal/rescue.rb:29:in `process_action'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_controller/metal/instrumentation.rb:32:in `block in process_action'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/notifications.rb:164:in `block in instrument'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/notifications.rb:164:in `instrument'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_controller/metal/instrumentation.rb:30:in `process_action'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_controller/metal/params_wrapper.rb:250:in `process_action'
 | /home/foreman/gems/gems/activerecord-4.2.8/lib/active_record/railties/controller_runtime.rb:18:in `process_action'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/abstract_controller/base.rb:137:in `process'
 | /home/foreman/gems/gems/actionview-4.2.8/lib/action_view/rendering.rb:30:in `process'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_controller/metal.rb:196:in `dispatch'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_controller/metal/rack_delegation.rb:13:in `dispatch'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_controller/metal.rb:237:in `block in action'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/routing/route_set.rb:74:in `call'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/routing/route_set.rb:74:in `dispatch'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/routing/route_set.rb:43:in `serve'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/routing/mapper.rb:49:in `serve'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/journey/router.rb:43:in `block in serve'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/journey/router.rb:30:in `each'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/journey/router.rb:30:in `serve'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/routing/route_set.rb:817:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/apipie-rails-0.4.0/lib/apipie/static_dispatcher.rb:65:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/rack/agent_hooks.rb:30:in `traced_call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/rack/browser_monitoring.rb:32:in `traced_call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/apipie-rails-0.4.0/lib/apipie/extractor/recorder.rb:132:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/apipie-rails-0.4.0/lib/apipie/middleware/checksum_in_headers.rb:27:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/rack-1.6.5/lib/rack/etag.rb:24:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/rack-1.6.5/lib/rack/conditionalget.rb:38:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/rack-1.6.5/lib/rack/head.rb:13:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/middleware/params_parser.rb:27:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/git/foreman/lib/middleware/catch_json_parse_errors.rb:8:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/middleware/flash.rb:260:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/rack-1.6.5/lib/rack/session/abstract/id.rb:225:in `context'
 | /home/foreman/gems/gems/rack-1.6.5/lib/rack/session/abstract/id.rb:220:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/middleware/cookies.rb:560:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/activerecord-4.2.8/lib/active_record/query_cache.rb:36:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/activerecord-4.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:653:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:88:in `__run_callbacks__'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:778:in `_run_call_callbacks'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/callbacks.rb:81:in `run_callbacks'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/middleware/callbacks.rb:27:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/middleware/remote_ip.rb:78:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/railties-4.2.8/lib/rails/rack/logger.rb:38:in `call_app'
 | /home/foreman/gems/gems/railties-4.2.8/lib/rails/rack/logger.rb:22:in `call'
 | /home/foreman/gems/gems/quiet_assets-1.1.0/lib/quiet_assets.rb:27:in `call_with_quiet_assets'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/git/foreman/lib/middleware/tagged_logging.rb:18:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/middleware/request_id.rb:21:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/rack-1.6.5/lib/rack/methodoverride.rb:22:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/rack-1.6.5/lib/rack/runtime.rb:18:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/activesupport-4.2.8/lib/active_support/cache/strategy/local_cache_middleware.rb:28:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/actionpack-4.2.8/lib/action_dispatch/middleware/static.rb:120:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/rack-1.6.5/lib/rack/sendfile.rb:113:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/secure_headers-3.6.2/lib/secure_headers/middleware.rb:12:in `call'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/railties-4.2.8/lib/rails/engine.rb:518:in `call'
 | /home/foreman/gems/gems/railties-4.2.8/lib/rails/application.rb:165:in `call'
 | /home/foreman/gems/gems/railties-4.2.8/lib/rails/railtie.rb:194:in `public_send'
 | /home/foreman/gems/gems/railties-4.2.8/lib/rails/railtie.rb:194:in `method_missing'
 | /home/foreman/gems/gems/newrelic_rpm-4.0.0.332/lib/new_relic/agent/instrumentation/middleware_tracing.rb:92:in `call'
 | /home/foreman/gems/gems/rack-1.6.5/lib/rack/urlmap.rb:66:in `block in call'
 | /home/foreman/gems/gems/rack-1.6.5/lib/rack/urlmap.rb:50:in `each'
 | /home/foreman/gems/gems/rack-1.6.5/lib/rack/urlmap.rb:50:in `call'
 | /root/.gem/gems/passenger-5.0.7/lib/phusion_passenger/rack/thread_handler_extension.rb:89:in `process_request'
 | /root/.gem/gems/passenger-5.0.7/lib/phusion_passenger/request_handler/thread_handler.rb:155:in `accept_and_process_next_request'
 | /root/.gem/gems/passenger-5.0.7/lib/phusion_passenger/request_handler/thread_handler.rb:110:in `main_loop'
 | /root/.gem/gems/passenger-5.0.7/lib/phusion_passenger/request_handler.rb:414:in `block (3 levels) in start_threads'
 | /root/.gem/gems/passenger-5.0.7/lib/phusion_passenger/utils.rb:111:in `block in create_thread_and_abort_on_exception'
 | /home/foreman/gems/gems/logging-2.2.0/lib/logging/diagnostic_context.rb:474:in `call'
 | /home/foreman/gems/gems/logging-2.2.0/lib/logging/diagnostic_context.rb:474:in `block in create_with_logging_context'
2017-04-05T13:46:03 a1c5a7ea [app] [I]   Rendered api/v2/errors/standard_error.json.rabl within api/v2/layouts/error_layout (0.7ms)
2017-04-05T13:46:03 a1c5a7ea [app] [I] Completed 500 Internal Server Error in 38ms (Views: 1.7ms | ActiveRecord: 10.6ms)

while this can also be a hammer bug which sends additional hashes, foreman should not generate 500 error