Failed to read FastCGI header after changing php mode to PHP-FPM

@24x7server, Disabling opcache is not a fix, but a work around.

@msbsmt, Are your running OPCache? Is DirectAdmin up to date? Maybe it would help to:

cd /usr/local/directadmin/custombuild
./build update
./build rewrite_confs
./build opcache
./build php n
./build apache