<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=534132) </details> <!--IssueSummary end--> <!--- Please read this! Before opening a new issue, make sure to search for keywords in the issues filtered by the "regression" or "type::bug" label: - https://gitlab.com/gitlab-org/gitlab/issues?label_name%5B%5D=regression - https://gitlab.com/gitlab-org/gitlab/issues?label_name%5B%5D=type::bug and verify the issue you're about to submit isn't a duplicate. ---> ### Summary For unknown reasons merge requests with notes and diffnotes will no longer load for a merge requests. This has been resolved in the past by deleting and re-creating the merge request. This does not seem to correlate with the number of notes or diffnotes. ### Steps to reproduce * Create merge request * add still unknown element to MR * comments will no longer load ### Example Project Unable to reproduce consistently ### What is the current _bug_ behavior? 500 error and comments will not longer load This happens on merge requests with as few as 18 notes. ### What is the expected _correct_ behavior? notes will load ### Relevant logs and/or screenshots <details><summary>Click to expand</summary> ``` app/models/concerns/discussion_on_diff.rb:50:in `truncated_diff_lines', app/serializers/base_serializer.rb:16:in `represent', app/controllers/concerns/notes_actions.rb:31:in `index', lib/gitlab/ip_address_state.rb:11:in `with', ee/app/controllers/ee/application_controller.rb:45:in `set_current_ip_address', app/controllers/application_controller.rb:487:in `set_current_admin', lib/gitlab/session.rb:11:in `with_session', app/controllers/application_controller.rb:478:in `set_session_storage', lib/gitlab/i18n.rb:114:in `with_locale', lib/gitlab/i18n.rb:120:in `with_user_locale', app/controllers/application_controller.rb:469:in `set_locale', app/controllers/application_controller.rb:462:in `set_current_context', lib/gitlab/middleware/action_controller_static_context.rb:23:in `call', ee/lib/omni_auth/strategies/group_saml.rb:41:in `other_phase', lib/gitlab/metrics/elasticsearch_rack_middleware.rb:16:in `call', lib/gitlab/middleware/sidekiq_shard_awareness_validation.rb:20:in `block in call', lib/gitlab/sidekiq_sharding/validator.rb:42:in `enabled', lib/gitlab/middleware/sidekiq_shard_awareness_validation.rb:20:in `call', lib/gitlab/middleware/memory_report.rb:13:in `call', lib/gitlab/middleware/speedscope.rb:13:in `call', lib/gitlab/database/load_balancing/rack_middleware.rb:23:in `call', lib/gitlab/middleware/rails_queue_duration.rb:33:in `call', lib/gitlab/etag_caching/middleware.rb:21:in `call', lib/gitlab/metrics/rack_middleware.rb:16:in `block in call', lib/gitlab/metrics/web_transaction.rb:46:in `run', lib/gitlab/metrics/rack_middleware.rb:16:in `call', lib/gitlab/middleware/go.rb:21:in `call', lib/gitlab/middleware/query_analyzer.rb:11:in `block in call', lib/gitlab/database/query_analyzer.rb:83:in `within', lib/gitlab/middleware/query_analyzer.rb:11:in `call', lib/ci/job_token/middleware.rb:11:in `call', lib/gitlab/middleware/multipart.rb:173:in `call', lib/gitlab/middleware/read_only/controller.rb:50:in `call', lib/gitlab/middleware/read_only.rb:18:in `call', lib/gitlab/middleware/unauthenticated_session_expiry.rb:18:in `call', lib/gitlab/middleware/same_site_cookies.rb:27:in `call', lib/gitlab/middleware/path_traversal_check.rb:40:in `call', lib/gitlab/middleware/handle_malformed_strings.rb:21:in `call', lib/gitlab/middleware/basic_health_check.rb:25:in `call', lib/gitlab/middleware/handle_ip_spoof_attack_error.rb:25:in `call', lib/gitlab/middleware/request_context.rb:15:in `call', lib/gitlab/middleware/webhook_recursion_detection.rb:15:in `call', config/initializers/fix_local_cache_middleware.rb:11:in `call', lib/gitlab/middleware/compressed_json.rb:44:in `call', lib/gitlab/middleware/rack_multipart_tempfile_factory.rb:19:in `call', lib/gitlab/middleware/sidekiq_web_static.rb:20:in `call', lib/gitlab/metrics/requests_rack_middleware.rb:83:in `call', lib/gitlab/middleware/release_env.rb:12:in `call ``` </details> [internal kibana link](https://log.gprd.gitlab.net/app/r/s/ymXjE) ### Output of checks <!--If you are reporting a bug on GitLab.com, uncomment below--> This bug happens on GitLab.com <!--and uncomment below if you have /label privileges--> <!--or follow up with an issue comment of `@gitlab-bot label ~"reproduced on GitLab.com"` if you do not--> #### Results of GitLab environment info <!--Input any relevant GitLab environment information if needed.--> <details> <summary>Expand for output related to GitLab environment info</summary> <pre> (For installations with omnibus-gitlab package run and paste the output of: \`sudo gitlab-rake gitlab:env:info\`) (For installations from source run and paste the output of: \`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production\`) </pre> </details> #### Results of GitLab application Check <!--Input any relevant GitLab application check information if needed.--> <details> <summary>Expand for output related to the GitLab application check</summary> <pre> (For installations with omnibus-gitlab package run and paste the output of: `sudo gitlab-rake gitlab:check SANITIZE=true`) (For installations from source run and paste the output of: `sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true`) (we will only investigate if the tests are passing) </pre> </details> ### Possible fixes <!--If you can, link to the line of code that might be responsible for the problem.--> <!--If you don't have /label privileges, follow up with an issue comment of `@gitlab-bot label ~"type::bug"`-->