MediaWiki internal error.

Original exception: BadTitleError: Den √łnskede sides titel var ikke tilladt, tom eller siden er forkert henvist fra en Post & Tele Museum p√• et andet sprog.
Den kan indeholde et eller flere tegn, som ikke kan anvendes i titler. in /domains/ptt-museum/wiki/web/includes/Wiki.php:197
Stack trace:
#0 /domains/ptt-museum/wiki/web/includes/Wiki.php(536): MediaWiki->performRequest()
#1 /domains/ptt-museum/wiki/web/includes/Wiki.php(446): MediaWiki->main()
#2 /domains/ptt-museum/wiki/web/index.php(61): MediaWiki->run()
#3 {main}

Exception caught inside exception handler: MWException: Detected bug in an extension! Hook Cite::checkRefsNoReferences has invalid call signature; Parameter 2 to Cite::checkRefsNoReferences() expected to be a reference, value given in /domains/ptt-museum/wiki/web/includes/Hooks.php:240
Stack trace:
#0 /domains/ptt-museum/wiki/web/includes/GlobalFunctions.php(3815): Hooks::run('ParserAfterPars...', Array)
#1 /domains/ptt-museum/wiki/web/includes/parser/Parser.php(371): wfRunHooks('ParserAfterPars...', Array)
#2 /domains/ptt-museum/wiki/web/includes/cache/MessageCache.php(873): Parser->parse('', Object(Title), Object(ParserOptions), true)
#3 /domains/ptt-museum/wiki/web/includes/Message.php(605): MessageCache->parse('Den \xC3\xB8nskede si...', Object(Title), true, true, Object(Language))
#4 /domains/ptt-museum/wiki/web/includes/Message.php(434): Message->parseText('Den \xC3\xB8nskede si...')
#5 /domains/ptt-museum/wiki/web/includes/Message.php(496): Message->toString()
#6 /domains/ptt-museum/wiki/web/includes/OutputPage.php(3528): Message->parseAsBlock()
#7 /domains/ptt-museum/wiki/web/includes/OutputPage.php(2062): OutputPage->addWikiMsgArray('badtitletext', NULL)
#8 /domains/ptt-museum/wiki/web/includes/Exception.php(342): OutputPage->showErrorPage(Object(Message), 'badtitletext', NULL)
#9 /domains/ptt-museum/wiki/web/includes/Exception.php(374): ErrorPageError->report()
#10 /domains/ptt-museum/wiki/web/includes/Exception.php(620): BadTitleError->report()
#11 /domains/ptt-museum/wiki/web/includes/Exception.php(690): MWExceptionHandler::report(Object(BadTitleError))
#12 /domains/ptt-museum/wiki/web/includes/Wiki.php(449): MWExceptionHandler::handle(Object(BadTitleError))
#13 /domains/ptt-museum/wiki/web/index.php(61): MediaWiki->run()
#14 {main}