My mediawiki (1.30.0) page is in Polish and the mediawiki converts page titles to url in 1:1 style - it means that page named Truteń will have url that contains Truteń with the Polish diacritic character "ń". This causes code 400 error to appear when I'm trying to preview pages that contain polish diacritic letters (ąęćśźżółń) in Facebook Sharing debbuger. Those also do not display informations from extensions (excerpts from pages while sharing). Miracously main page works, even though it has diacritic characters in its url ("Strona główna").
How can I disable those characters? I can also add that I'm almost total newbie and am using OVH services (the cheapest plan they had). Here is an example page - http://wiki.mrowki.ovh/index.php?title=Truteń