Bug in files /usr/local/ispconfig/interface/web/admin/lib/lang/{all languages}_system_config.lng. There is no translation of "System Config" [+SOLVED]
Tab System
The solution to the problem:
You need to add the line
$wb['System Config'] = 'System Config'; in files /usr/local/ispconfig/interface/web/admin/lib/lang/{en, de, ru, etc}_system_config.lng