PHP errors are by default set to go to the apache error log. On Ubuntu, the error log is located at /var/log/apache2/error.log. If you are a PHP developer, it is good idea to open a small terminal window and type the following:
tail -f /var/log/apache2/error.logThis would essentially give you a live view of the error log. As you generate errors, you would see the error messages on the terminal.