After cPanel upgrade if you are getting following error while accessing the ConfigServer Security & Firewall plugin.

Internal Server Error: “GET /cpsess3970557455/cgi/addon_csf.cgi HTTP/1.1” 500 No response from subprocess (/usr/local/cpanel/whostmgr/docroot/cgi/addon_csf.cgi): subprocess exited with status 2

You may try to use the following workaround.

Disable the firewall

/usr/sbin/csf -x

Installe the perl modules Net::LibIDN & URI

/scripts/perlinstaller –force Net::LibIDN
/scripts/perlinstaller –force URI

Enable the firewall

/usr/sbin/csf -e

Upgrade the firewall

/usr/sbin/csf -u

This should resolve the issue with the plugin.. well at least it did for me 😉