MediaWiki internal error.

Original exception: [6bdb5135] /mediawiki/index.php?title=Tools&action=edit MWException from line 226 of /var/www/html/mediawiki-1.25.2/includes/Hooks.php: Detected bug in an extension! Hook ImageMap::onParserFirstCallInit has invalid call signature; Parameter 1 to ImageMap::onParserFirstCallInit() expected to be a reference, value given
Backtrace:
#0 /var/www/html/mediawiki-1.25.2/includes/parser/Parser.php(310): Hooks::run(string, array)
#1 /var/www/html/mediawiki-1.25.2/includes/StubObject.php(105): Parser->firstCallInit()
#2 /var/www/html/mediawiki-1.25.2/includes/StubObject.php(129): StubObject->_call(string, array)
#3 /var/www/html/mediawiki-1.25.2/includes/cache/MessageCache.php(1009): StubObject->__call(string, array)
#4 /var/www/html/mediawiki-1.25.2/includes/cache/MessageCache.php(986): MessageCache->getParser()
#5 /var/www/html/mediawiki-1.25.2/includes/Message.php(1058): MessageCache->transform(string, boolean, Language, NULL)
#6 /var/www/html/mediawiki-1.25.2/includes/Message.php(726): Message->transformText(string)
#7 /var/www/html/mediawiki-1.25.2/includes/Message.php(789): Message->toString()
#8 /var/www/html/mediawiki-1.25.2/includes/User.php(4575): Message->text()
#9 /var/www/html/mediawiki-1.25.2/includes/User.php(4615): User::getGroupPage(string)
#10 [internal function]: User::makeGroupLinkWiki(string)
#11 /var/www/html/mediawiki-1.25.2/includes/Title.php(2410): array_map(array, array)
#12 /var/www/html/mediawiki-1.25.2/includes/Title.php(2003): Title->missingPermissionError(string, boolean)
#13 /var/www/html/mediawiki-1.25.2/includes/Title.php(2485): Title->checkQuickPermissions(string, User, array, string, boolean)
#14 /var/www/html/mediawiki-1.25.2/includes/Title.php(1922): Title->getUserPermissionsErrorsInternal(string, User, string)
#15 /var/www/html/mediawiki-1.25.2/includes/EditPage.php(571): Title->getUserPermissionsErrors(string, User, string)
#16 /var/www/html/mediawiki-1.25.2/includes/EditPage.php(508): EditPage->getEditPermissionErrors(string)
#17 /var/www/html/mediawiki-1.25.2/includes/actions/EditAction.php(56): EditPage->edit()
#18 /var/www/html/mediawiki-1.25.2/includes/MediaWiki.php(395): EditAction->show()
#19 /var/www/html/mediawiki-1.25.2/includes/MediaWiki.php(273): MediaWiki->performAction(Article, Title)
#20 /var/www/html/mediawiki-1.25.2/includes/MediaWiki.php(566): MediaWiki->performRequest()
#21 /var/www/html/mediawiki-1.25.2/includes/MediaWiki.php(414): MediaWiki->main()
#22 /var/www/html/mediawiki-1.25.2/index.php(41): MediaWiki->run()
#23 {main}

Exception caught inside exception handler: [e29b234c] /mediawiki/index.php?title=Tools&action=edit MWException from line 226 of /var/www/html/mediawiki-1.25.2/includes/Hooks.php: Detected bug in an extension! Hook Cite::clearState has invalid call signature; Parameter 1 to Cite::clearState() expected to be a reference, value given
Backtrace:
#0 /var/www/html/mediawiki-1.25.2/includes/parser/Parser.php(376): Hooks::run(string, array)
#1 /var/www/html/mediawiki-1.25.2/includes/parser/Parser.php(5025): Parser->clearState()
#2 /var/www/html/mediawiki-1.25.2/includes/parser/Parser.php(631): Parser->startParse(Title, ParserOptions, integer, boolean)
#3 /var/www/html/mediawiki-1.25.2/includes/parser/Parser.php(5051): Parser->preprocess(string, Title, ParserOptions)
#4 /var/www/html/mediawiki-1.25.2/includes/cache/MessageCache.php(994): Parser->transformMsg(string, ParserOptions, Title)
#5 /var/www/html/mediawiki-1.25.2/includes/Message.php(1058): MessageCache->transform(string, boolean, Language, Title)
#6 /var/www/html/mediawiki-1.25.2/includes/Message.php(726): Message->transformText(string)
#7 /var/www/html/mediawiki-1.25.2/includes/Message.php(789): Message->toString()
#8 /var/www/html/mediawiki-1.25.2/includes/OutputPage.php(928): Message->text()
#9 /var/www/html/mediawiki-1.25.2/includes/OutputPage.php(975): OutputPage->setHTMLTitle(Message)
#10 /var/www/html/mediawiki-1.25.2/includes/OutputPage.php(2330): OutputPage->setPageTitle(string)
#11 /var/www/html/mediawiki-1.25.2/includes/exception/MWException.php(195): OutputPage->prepareErrorPage(string)
#12 /var/www/html/mediawiki-1.25.2/includes/exception/MWException.php(245): MWException->reportHTML()
#13 /var/www/html/mediawiki-1.25.2/includes/exception/MWExceptionHandler.php(59): MWException->report()
#14 /var/www/html/mediawiki-1.25.2/includes/exception/MWExceptionHandler.php(169): MWExceptionHandler::report(MWException)
#15 /var/www/html/mediawiki-1.25.2/includes/MediaWiki.php(428): MWExceptionHandler::handleException(MWException)
#16 /var/www/html/mediawiki-1.25.2/index.php(41): MediaWiki->run()
#17 {main}