<!--- Please read this! Before opening a new issue, make sure to search for keywords in the issues filtered by the "regression" or "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=bug and verify the issue you're about to submit isn't a duplicate. ---> ### Summary Once the wiki of a project has been disabled it cannot be re-enabled through the UI without receiving a `Something has gone wrong on our end` error. ### Steps to reproduce 1. Create a project on GitLab.com. 1. Disable the wiki on that project. 1. Attempt to re-enable the wiki. 1. Observe error message. ### Example Project [gitlab-gold/wiki-test](https://gitlab.com/gitlab-gold/wiki-test) ### What is the current *bug* behavior? The wiki of a project is not able to be re-enabled after being disabled. ### What is the expected *correct* behavior? The wiki of a project should be able to be disabled and then re-enabled without error. ### Relevant logs and/or screenshots  ### Output of checks This bug happens on GitLab.com: 13.4.0-pre `d20e5bc90ef` ### Workaround Enabling the Wiki via the [Projects API](https://docs.gitlab.com/ee/api/projects.html#edit-project) still works: ``` curl --request PUT \ --url 'https://gitlab.com/api/v4/projects/PROJECT_ID?wiki_enabled=yes' \ --header 'authorization: Bearer TOKEN' ``` ZD: https://gitlab.zendesk.com/agent/tickets/170197 (GitLab Internal)