So I was receiving this error after cPanel upgraded:

Internal Server Error

500

No response from subprocess (/usr/local/cpanel/whostmgr/docroot/cgi/addon_csf.cgi): subprocess exited with status 2

This did not fix it:

/usr/sbin/csf -x
/scripts/perlinstaller --force URI
/usr/sbin/csf -e
/usr/sbin/csf -u

If that doesn’t work this will:

curl -s configserver.com/free/csupdate | perl