PHP Warning: Module already loaded in Unknown on line 0

I think you have loaded Xdebug probably twice in php.ini.

1. check the php.ini, that not have set xdebug.so for the values extension= and zend_extension=.

2. Check also /etc/php5/apache2 and /etc/php5/cli/. You should not load in each php.ini in these directories the extension xdebug.so. Only one file, php.ini should load it.

   Note: Inside the path is the string /etc/php5. The 5 is the version of PHP. So if you use another version, you always get a different path, like php7.