Up to the end, it is impossible to understand what exactly the bug is, but maybe someone has come across such a bug. If you enter Russian characters in the address bar, namely the letter "X" (after which there must be some other characters), then an error is returned.
http: // localhost / dilapidated
Not found
The requested URL was not found on this server.
This problem is only with one character, and if autoload is used, you can check it using some framework.
Without the letter "X" page opens normally.
In a lower version of php, there is no such problem, but again the problem may not be in PHP, but in the apache or OS itself.
urlencodeor transliteration, and it is not clear how routing php or apache performs routing, etc. those. For the full question, I think you need to give the methods of processing requests and configurations most likely you have in the route a typoветхийwhereхLatin X and not Russian. You can check by expanding the string in hex and compare the character codes of the source string and the string entered in the browser - Naumov