Infinite loop: list of questions "related" to "removed" question contains the removed question itself

Question

This question, titled How did ancient China invent such wonders as fear systems and calendar before ancient Europe? has been removed and the 404 it leads to contains a list of some similar questions that might be relevant. Oddly enough, the aforementioned list again contains the removed question. Further, the "related questions" suggestions on the right side column on different pages also contain the deleted question.

Judging by the "id" (or whatever else that number xxx in the URL format topic.se.com/questions/xxx/question-text is called) of the removed question: 35044, and assuming that these numbers increase over time, it is not a very recent question, at least a few months old. So this is most likely a bug, not a caching issue.

Naively, the most straightforward solution would be to have the database query that generates the list of related questions also check the field for whether a question is removed.

Answer 1

So, funny thing about that: the question listed as related is actually a different question (id 35100) that happens to be closed as a duplicate of the deleted one. It appears you aren't logged in on that site, so as the question is closed as a duplicate and has no answers, it automatically redirects to the target.

There are the obvious fixes we could apply here for this specific question - such as reopening or undeleting the individual questions involved. But there's some merit in checking for a technical, global fix as well... and there I see a few different options. In no particular order:

• prevent Community user deletion (which is what happened here) of questions that are targets of duplicate closures;
• add the noredirect parameter to the links in the sidebar or the 404 page;
• don't redirect anonymous users to duplicate targets if the target is deleted; or
• avoid adding questions closed as duplicates of deleted questions into the Related list.

I don't know off-hand which approach would be best (nor do I have the code in front of me to see which would be more feasible than the others), but figured I'd write this up for future reference.

Thanks for the report!