内部エラー

[942d1d48c9564d5b0d377c21] /index.php?title=Javascript%E3%82%B3%E3%83%BC%E3%83%87%E3%82%A3%E3%83%B3%E3%82%B0%E8%A6%8F%E7%B4%84 Error from line 287 of /home/ubuntu/z-ton/extensions/SyntaxHighlight_GeSHi/SyntaxHighlight_GeSHi.class.php: Class "Symfony\Component\Process\ProcessBuilder" not found

Backtrace:

#0 /home/ubuntu/z-ton/extensions/SyntaxHighlight_GeSHi/SyntaxHighlight_GeSHi.class.php(127): SyntaxHighlight_GeSHi::highlight()
#1 /home/ubuntu/z-ton/includes/parser/Parser.php(3888): SyntaxHighlight_GeSHi::parserHook()
#2 /home/ubuntu/z-ton/includes/parser/Preprocessor_DOM.php(1362): Parser->extensionSubstitution()
#3 /home/ubuntu/z-ton/includes/parser/Parser.php(2942): PPFrame_DOM->expand()
#4 /home/ubuntu/z-ton/includes/parser/Parser.php(1293): Parser->replaceVariables()
#5 /home/ubuntu/z-ton/includes/parser/Parser.php(443): Parser->internalParse()
#6 /home/ubuntu/z-ton/includes/content/WikitextContent.php(323): Parser->parse()
#7 /home/ubuntu/z-ton/includes/content/AbstractContent.php(516): WikitextContent->fillParserOutput()
#8 /home/ubuntu/z-ton/includes/poolcounter/PoolWorkArticleView.php(141): AbstractContent->getParserOutput()
#9 /home/ubuntu/z-ton/includes/poolcounter/PoolCounterWork.php(123): PoolWorkArticleView->doWork()
#10 /home/ubuntu/z-ton/includes/page/Article.php(604): PoolCounterWork->execute()
#11 /home/ubuntu/z-ton/includes/actions/ViewAction.php(68): Article->view()
#12 /home/ubuntu/z-ton/includes/MediaWiki.php(500): ViewAction->show()
#13 /home/ubuntu/z-ton/includes/MediaWiki.php(294): MediaWiki->performAction()
#14 /home/ubuntu/z-ton/includes/MediaWiki.php(818): MediaWiki->performRequest()
#15 /home/ubuntu/z-ton/includes/MediaWiki.php(524): MediaWiki->main()
#16 /home/ubuntu/z-ton/index.php(42): MediaWiki->run()
#17 {main}