MediaWiki internal error.

Original exception: [f433cbc1] /wiki/Special:Senaste_relaterade_%EF%BF%BD%EF%BF%BDndringar/Kemistklubben Exception from line 192 of /home/web/studentkaren.fi/wiki/includes/Wiki.php: The requested page title was invalid, empty, or an incorrectly linked inter-language or inter-wiki title.
It may contain one or more characters that cannot be used in titles.
Backtrace:
#0 /home/web/studentkaren.fi/wiki/includes/Wiki.php(588): MediaWiki->performRequest()
#1 /home/web/studentkaren.fi/wiki/includes/Wiki.php(447): MediaWiki->main()
#2 /home/web/studentkaren.fi/wiki/index.php(46): MediaWiki->run()
#3 {main}

Exception caught inside exception handler: [4923818a] /wiki/Special:Senaste_relaterade_%EF%BF%BD%EF%BF%BDndringar/Kemistklubben Exception from line 222 of /home/web/studentkaren.fi/wiki/includes/Hooks.php: Detected bug in an extension! Hook Cite::checkRefsNoReferences has invalid call signature; Parameter 2 to Cite::checkRefsNoReferences() expected to be a reference, value given
Backtrace:
#0 /home/web/studentkaren.fi/wiki/includes/GlobalFunctions.php(4004): Hooks::run()
#1 /home/web/studentkaren.fi/wiki/includes/parser/Parser.php(396): wfRunHooks()
#2 /home/web/studentkaren.fi/wiki/includes/cache/MessageCache.php(1070): Parser->parse()
#3 /home/web/studentkaren.fi/wiki/includes/Message.php(963): MessageCache->parse()
#4 /home/web/studentkaren.fi/wiki/includes/Message.php(667): Message->parseText()
#5 /home/web/studentkaren.fi/wiki/includes/Message.php(756): Message->toString()
#6 /home/web/studentkaren.fi/wiki/includes/OutputPage.php(3611): Message->parseAsBlock()
#7 /home/web/studentkaren.fi/wiki/includes/OutputPage.php(2164): OutputPage->addWikiMsgArray()
#8 /home/web/studentkaren.fi/wiki/includes/exception/ErrorPageError.php(58): OutputPage->showErrorPage()
#9 /home/web/studentkaren.fi/wiki/includes/exception/BadTitleError.php(48): ErrorPageError->report()
#10 /home/web/studentkaren.fi/wiki/includes/exception/MWExceptionHandler.php(44): BadTitleError->report()
#11 /home/web/studentkaren.fi/wiki/includes/exception/MWExceptionHandler.php(139): MWExceptionHandler::report()
#12 /home/web/studentkaren.fi/wiki/includes/Wiki.php(454): MWExceptionHandler::handle()
#13 /home/web/studentkaren.fi/wiki/index.php(46): MediaWiki->run()
#14 {main}