While enabling PHP SuPHP handler on one of my server, I started to get 500 Internal Server Error for all php pages .
So, my initial reaction was to check the Permissions and Ownerships for all PHP files as while enabling PHP SuPHP the max file permissions should be 644 and max folder permissions should be 755 and all php files should ran under the ownership of user.user instead of apache.apache.
Also, I have checked all .htaccess files to see any one of the contains PHP flags like php_flag or php_admin_value as while enabling PHP SuPHP all PHP flags defined under .htaccess files will result in a 500 Internal Server Error .
But after checking all the above, I started to wonder as to what it could be and then I realized that it could be the RLimitMEM and RLimitCPU defined in the httpd.conf file and after disabling those values all the PHP pages started to work like a charm.
So, if anyone come across this issue then follow the below steps to resolve the issue :
Open the httpd.conf file
root@server[#] vi /etc/httpd/conf/httpd.conf
and search for lines
RLimitMEM 116574208 RLimitCPU 240
and comment those lines as
#RLimitMEM 116574208 #RLimitCPU 240
save and quit.
finally restart apache service
root@server[#] /etc/init.d/httpd restart