[7039940808f50056f9e82724] /w/index.php?oldid=13355 Error from line 640 of /var/www/liandri/w/includes/exception/MWExceptionHandler.php: Class 'FormatJson' not found

Backtrace:

#0 /var/www/liandri/w/includes/exception/MWExceptionHandler.php(197): MWExceptionHandler::logError()
#1 /var/www/liandri/w/includes/AutoLoader.php(81): MWExceptionHandler::handleError()
#2 /var/www/liandri/w/includes/AutoLoader.php(81): require()
#3 [internal function]: AutoLoader::autoload()
#4 /var/www/liandri/w/includes/exception/MWExceptionHandler.php(604): spl_autoload_call()
#5 /var/www/liandri/w/includes/exception/MWExceptionHandler.php(111): MWExceptionHandler::logException()
#6 /var/www/liandri/w/includes/exception/MWExceptionHandler.php(129): MWExceptionHandler::rollbackMasterChangesAndLog()
#7 /var/www/liandri/w/includes/MediaWiki.php(551): MWExceptionHandler::handleException()
#8 /var/www/liandri/w/index.php(43): MediaWiki->run()
#9 {main}