After installing dataTransfer, I get the folowing error in the configurator (right after the language selection) :
[5e540dcc8e05b8542ef51b37] /mediawiki/mw-config/?page=ExistingWiki Error from line 118 of /var/www/html/mediawiki/extensions/DataTransfer/DataTransfer.php: Class 'DT_LanguageEn' not foundBacktrace:#0 /var/www/html/mediawiki/extensions/DataTransfer/DataTransfer.php(86): dtfInitContentLanguage(string)#1 /var/www/html/mediawiki/LocalSettings.php(133): include_once(string)#2 /var/www/html/mediawiki/includes/installer/Installer.php(599): require(string)#3 /var/www/html/mediawiki/includes/installer/WebInstallerExistingWiki.php(29): Installer::getExistingLocalSettings()#4 /var/www/html/mediawiki/includes/installer/WebInstaller.php(279): WebInstallerExistingWiki->execute()#5 /var/www/html/mediawiki/mw-config/index.php(80): WebInstaller->execute(array)#6 /var/www/html/mediawiki/mw-config/index.php(38): wfInstallerMain()#7 {main}