From https://mhargiss.beta.instructure.com/error_reports

error

        undefined method `workflow_state' for nil:NilClass
        /var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/app/controllers/quizzes/quiz_submissions_api_controller.rb:176:in `index'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_controller/metal/implicit_render.rb:4:in `send_action'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/abstract_controller/base.rb:167:in `process_action'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_controller/metal/rendering.rb:10:in `process_action'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/abstract_controller/callbacks.rb:18:in `block in process_action'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activesupport/lib/active_support/callbacks.rb:735:in `block (2 levels) in _run__372899202833364372__process_action__2768185178532023428__callbacks'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activesupport/lib/active_support/callbacks.rb:215:in `block in _conditional_callback_around_12169'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/app/controllers/application_controller.rb:253:in `set_locale'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activesupport/lib/active_support/callbacks.rb:214:in `_conditional_callback_around_12169'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activesupport/lib/active_support/callbacks.rb:470:in `block in _run__372899202833364372__process_action__2768185178532023428__callbacks'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activesupport/lib/active_support/callbacks.rb:215:in `block in _conditional_callback_around_12168'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/marginalia-1.3.0/lib/marginalia.rb:77:in `record_query_comment'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activesupport/lib/active_support/callbacks.rb:214:in `_conditional_callback_around_12168'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activesupport/lib/active_support/callbacks.rb:447:in `_run__372899202833364372__process_action__2768185178532023428__callbacks'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activesupport/lib/active_support/callbacks.rb:405:in `__run_callback'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activesupport/lib/active_support/callbacks.rb:385:in `_run_process_action_callbacks'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activesupport/lib/active_support/callbacks.rb:81:in `run_callbacks'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/abstract_controller/callbacks.rb:17:in `process_action'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_controller/metal/rescue.rb:29:in `process_action'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_controller/metal/instrumentation.rb:30:in `block in process_action'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activesupport/lib/active_support/notifications.rb:123:in `block in instrument'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activesupport/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activesupport/lib/active_support/notifications.rb:123:in `instrument'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_controller/metal/instrumentation.rb:29:in `process_action'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_controller/metal/params_wrapper.rb:207:in `process_action'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activerecord/lib/active_record/railties/controller_runtime.rb:18:in `process_action'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/abstract_controller/base.rb:121:in `process'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/abstract_controller/rendering.rb:45:in `process'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/rack-mini-profiler-0.9.2/lib/mini_profiler/profiling_methods.rb:79:in `block in profile_method'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_controller/metal.rb:203:in `dispatch'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_controller/metal.rb:246:in `block in action'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_dispatch/routing/route_set.rb:73:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_dispatch/routing/route_set.rb:73:in `dispatch'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_dispatch/routing/route_set.rb:36:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/journey-1.0.4/lib/journey/router.rb:68:in `block in call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/journey-1.0.4/lib/journey/router.rb:56:in `each'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/journey-1.0.4/lib/journey/router.rb:56:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_dispatch/routing/route_set.rb:608:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/gems/plugins/respondus_soap_endpoint/lib/respondus_soap_endpoint/middleware.rb:61:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/rack-1.4.5/lib/rack/etag.rb:23:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/rack-1.4.5/lib/rack/conditionalget.rb:25:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_dispatch/middleware/head.rb:14:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_dispatch/middleware/params_parser.rb:21:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/lib/canvas/request_throttle.rb:60:in `block in call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/lib/canvas/request_throttle.rb:258:in `reserve_capacity'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/lib/canvas/request_throttle.rb:55:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_dispatch/middleware/flash.rb:242:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/rack-1.4.5/lib/rack/session/abstract/id.rb:210:in `context'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/rack-1.4.5/lib/rack/session/abstract/id.rb:205:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/encrypted_cookie_store-instructure-1.1.10/lib/encrypted_cookie_store.rb:47:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/app/middleware/sessions_timeout.rb:22:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/gems/plugins/multiple_root_accounts/lib/load_account_with_domain.rb:158:in `block in call'
/var/web/canvas/shared/bundle/ruby/2.1.0/gems/switchman-1.2.35/app/models/switchman/shard.rb:57:in `activate'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/gems/plugins/multiple_root_accounts/lib/load_account_with_domain.rb:151:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_dispatch/middleware/cookies.rb:341:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activerecord/lib/active_record/query_cache.rb:64:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb:479:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activesupport/lib/active_support/callbacks.rb:405:in `_run__4322442312634277793__call__2525760471295386074__callbacks'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activesupport/lib/active_support/callbacks.rb:405:in `__run_callback'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activesupport/lib/active_support/callbacks.rb:385:in `_run_call_callbacks'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/activesupport/lib/active_support/callbacks.rb:81:in `run_callbacks'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_dispatch/middleware/callbacks.rb:27:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_dispatch/middleware/remote_ip.rb:31:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/actionpack/lib/action_dispatch/middleware/show_exceptions.rb:56:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/railties/lib/rails/rack/logger.rb:32:in `call_app'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/railties/lib/rails/rack/logger.rb:18:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/request_store-1.1.0/lib/request_store/middleware.rb:8:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/app/middleware/request_context_generator.rb:36:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/rack-1.4.5/lib/rack/methodoverride.rb:21:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/app/middleware/prevent_non_multipart_parse.rb:32:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/rack-1.4.5/lib/rack/runtime.rb:17:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/rack-1.4.5/lib/rack/lock.rb:15:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/rack-cache-1.2/lib/rack/cache/context.rb:136:in `forward'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/rack-cache-1.2/lib/rack/cache/context.rb:245:in `fetch'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/rack-cache-1.2/lib/rack/cache/context.rb:185:in `lookup'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/rack-cache-1.2/lib/rack/cache/context.rb:66:in `call!'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/rack-cache-1.2/lib/rack/cache/context.rb:51:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/bundle/ruby/2.1.0/gems/rack-mini-profiler-0.9.2/lib/mini_profiler/profiler.rb:193:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/railties/lib/rails/engine.rb:484:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/railties/lib/rails/application.rb:231:in `call'
/var/web/canvas/releases/2015-07-16_174812_26b4ef4a508d509b/vendor/cache/rails-b344986bc3d9/railties/lib/rails/railtie/configurable.rb:30:in `method_missing'
/usr/lib/ruby/vendor_ruby/phusion_passenger/rack/thread_handler_extension.rb:94:in `process_request'
/usr/lib/ruby/vendor_ruby/phusion_passenger/request_handler/thread_handler.rb:149:in `accept_and_process_next_request'
/usr/lib/ruby/vendor_ruby/phusion_passenger/request_handler/thread_handler.rb:110:in `main_loop'
/usr/lib/ruby/vendor_ruby/phusion_passenger/request_handler.rb:414:in `block (3 levels) in start_threads'
/usr/lib/ruby/vendor_ruby/phusion_passenger/utils.rb:111:in `block in create_thread_and_abort_on_exception'