I'd like to exemplify with:
PHP Warning Cannot modify header information
The meta topic here would be that it's caused by language misdesign, but anyway it's a real issue. The web and most bulletin boards are polluted with question like this, and despite better base design even Stackoverflow is affected. Two solutions:
Let's be honest. The influx of these questions is caused by laziness. Posting a new question on Stackoverflow always brings up matching duplicates for "Warning Cannot modify header information". Some askers just refuse to use that feature and the search function. Or expect other people to debug for them, explain basic language features or want prosaic recitations of the manual.
Anyway, filtering might help here. A simple regex check on question and question title should suffice to detect the majority of these excessive duplicates. (We'll have to make a list though.) And if the new question form detects it, it should just bring up an extra confirmation box:
The system detected that your question is most likely a duplicate. If you have used the search function before and checked out some of the suggested links, then check this box [x]. Otherwise please do so now. Your question would likely be closed without answers if it's a repetitive duplicate.
Well, it works for spammers. And I assume it's at least likely to reduce the amount of annoying duplicates. So, let's not postpone the list making.
Evil Plan B
This is not an proposal, nor an announcement, but it's not a fun answer either.
Be realistic. Excessive duplicate questions are actively encouraged by the SO commmunity. Whenever one of those boring, stupid or annoying duplicate questions is posted, 10 people jump immediately to the rescue and answer it. (While the more interesting questions seemingly go ignored on weeks.)
But that's only natural. Gaining reputation is fun, and that's why people flock to simple (and sometimes dull) questions.
However this very human behaviour draws boring askers to Stackoverflow. If you reward them, they will come. And closevoting questions is no serious discouragement. Likewise are admonishing comments no functional repellent. Therefore I charily suggest "censoring" the overhelpful answers on useless duplicates. If a duplicate is closevoted quickly enough it's redundant. But if someone answers it, it's imperative to kill off those answers on the spot. I'd use something along a standard replacement template like:
Search for [php] Warning Cannot modify header information
The question is a duplicate and has been asked too many times before. +1 for effort on this answer, but links should be sufficient here.
Needs rewording. It partially punishes the answerer, but should make it clear that the purpose is censoring the stupid question. And one needs to take care not to wipe the sporadic extraordinarily good answers, and whatnot. If the answerer is appalled by this method, a discussion may ensue, or he can just revert it back if it seems unjust.
Yet, I think this is the only realistic deterrant against <PROBLEM OF THE WEEK>. A real stop to answering stupid duplicates will send a clear message. A blood font might also help.
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