which one of these:
1.Your server has disabled a core PHP function exec via the disable_functions directive in php.ini. This may cause unexpected problems in XenForo.
2.Your server has disabled a core PHP function escapeshellarg via the disable_functions directive in php.ini. This may cause unexpected problems in XenForo.
3.Your server has disabled a core PHP function proc_open via the disable_functions directive in php.ini. This may cause unexpected problems in XenForo.
4.Your server has disabled a core PHP function popen via the disable_functions directive in php.ini. This may cause unexpected problems in XenForo.