Yesterday I updated Xubuntu 13.10 to Xubuntu 14.04 in my laptop, after the update I tried to use xdebug but Netbeans was not able to connect. I started checking, the package was installed, the configuration was set in the /etc/php5/apache2/php.ini but even with that it was not working.

After some time checking some other posts, I was finally redirected to the wizard in the xdebug site, and after checking my configuration I saw the missing configuration causing the issue.

By some reason the soft link to xdebug.ini file was not created properly, so apache was not able to load xdebug, so I just fixed it by creating the required link to the configuration file that loads the extension and then just restarted apache.

cd /etc/php5/apache2/conf.d
sudo ln -s ../../mods-available/xdebug.ini 20-xdebug.ini
sudo service apache2 restart

Finally I was able to use Netbeans PHP debug functionality again.

I hope this helps someone.