After using OpenProject Wiki for some weeks without problems I added a new Wiki entry named "!" (just the exclamation mark) in order to show this entry at the top of the Wiki TOC on the left.
Not a good idea! I can now not access the project at all, just getting "Internal error" when selecting the project.
The log shows the message "ERROR - - : ... No route matches ... title: "!" ...

feb 19 11:18:37 cyborg-N141CU openproject-web-1.service[981]: E, [2021-02-19T11:18:37.764145 #24995] ERROR -- : [current_user=Anonymous] No route matches {:action=>"show", :controller=>"wiki", :id=>#<WikiPage id: 89, wiki_id: 7, title: "!", created_at: "2021-02-19 09:06:59", protected: false, parent_id: 4, slug: "", updated_at: "2021-02-19 09:06:59">, :project_id=>#<Project id: 8, name: "Nabben-Hb", description: "Projektet syftar initialt, i Förstudien, till att ...", public: true, parent_id: nil, created_at: "2021-01-03 10:03:12", updated_at: "2021-01-12 12:52:37", identifier: "nabben-hb", lft: 13, rgt: 14, active: true, templated: false>}, possible unmatched constraints: [:id]: No route matches {:action=>"show", :controller=>"wiki", :id=>#<WikiPage id: 89, wiki_id: 7, title: "!", created_at: "2021-02-19 09:06:59", protected: false, parent_id: 4, slug: "", updated_at: "2021-02-19 09:06:59">, :project_id=>#<Project id: 8, name: "Nabben-Hb", description: "Projektet syftar initialt, i Förstudien, till att ...", public: true, parent_id: nil, created_at: "2021-01-03 10:03:12", updated_at: "2021-01-12 12:52:37", identifier: "nabben-hb", lft: 13, rgt: 14, active: true, templated: false>}, possible unmatched constraints: [:id]

What can I do to make OpenProject work again?

Some ideas (my knowledge of OpenProject, Wiki or postgre is not good enough to figure out how to do)
* Use an openproject command operating on the Wiki ? (I have not found a suitable command)
* Remove this entry from the database (postgre? SQL command?)
* Change "!" to "A" in the faulty entry directly in the database (I have no idea of how the database is organised with indexes etc)
* Reset database version ?? (There are some files in .../postgresql/10/main/base/ that I guess are backup files, one of them just one day old)

If the "!" or other entries create problems like this it seems to be a good idea to check entry names before storing them in the database. BUG ?

I appreciate any help on this issue.