Open Terminal and enter the following in a single line:

/System/Library/CoreServices/Menu\ Extras/User.menu/Contents/Resources/CGSession -suspend

Open Terminal

sudo mv httpd-mpm.conf httpd-mpm.conf.elcapitan

sudo cp httpd-mpm.conf~orig httpd-mpm.conf

 and then entered the commands:

sudo apachectl restart

apachectl configtest

The last command returned "Syntax OK". Now work Done!