<!--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=325105) </details> <!--IssueSummary end--> There are cases when we terminate the websocket connection to the client on our own: - changed authentication settings - cannot read / write from the upstream terminal provider - session timeout (to be added) We should use close codes to communicate the reason why the connection was closed to our frontend. See https://gitlab.com/gitlab-org/gitlab-ce/issues/26277#note_21331208. ### References https://tools.ietf.org/html/rfc6455#section-7.4.1