MediaWiki internal error.

Original exception: [68f774e0] /wiki/Special:Bevakningslista Exception from line 346 of /home/web/studentkaren.fi/wiki/includes/specialpage/SpecialPage.php: Please <a href="/wiki/index.php?title=Special:Inloggning&amp;returnto=Special%3ABevakningslista" title="Special:Inloggning">logga in</a> to view or edit items on your watchlist.
Backtrace:
#0 /home/web/studentkaren.fi/wiki/includes/specials/SpecialWatchlist.php(44): SpecialPage->requireLogin()
#1 /home/web/studentkaren.fi/wiki/includes/specialpage/SpecialPage.php(379): SpecialWatchlist->execute()
#2 /home/web/studentkaren.fi/wiki/includes/specialpage/SpecialPageFactory.php(503): SpecialPage->run()
#3 /home/web/studentkaren.fi/wiki/includes/Wiki.php(285): SpecialPageFactory::executePath()
#4 /home/web/studentkaren.fi/wiki/includes/Wiki.php(588): MediaWiki->performRequest()
#5 /home/web/studentkaren.fi/wiki/includes/Wiki.php(447): MediaWiki->main()
#6 /home/web/studentkaren.fi/wiki/index.php(46): MediaWiki->run()
#7 {main}

Exception caught inside exception handler: [a9a89aa0] /wiki/Special:Bevakningslista 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(2162): Message->parseAsBlock()
#7 /home/web/studentkaren.fi/wiki/includes/exception/ErrorPageError.php(58): OutputPage->showErrorPage()
#8 /home/web/studentkaren.fi/wiki/includes/exception/MWExceptionHandler.php(44): ErrorPageError->report()
#9 /home/web/studentkaren.fi/wiki/includes/exception/MWExceptionHandler.php(139): MWExceptionHandler::report()
#10 /home/web/studentkaren.fi/wiki/includes/Wiki.php(454): MWExceptionHandler::handle()
#11 /home/web/studentkaren.fi/wiki/index.php(46): MediaWiki->run()
#12 {main}