PHP not displaying errors - Internal Server Error (500)
The php.ini snippet you pasted has a semicolon (the ; character) in each line. The semicolon is the start of a comment in php.ini, so everything in a line following a semicolon is not used. Try manually setting display_errors to on and error_reporting to E_ALL, or removing the appropriate semicolons to fix this.
Furthermore, check your apache's error log, php might be logging its errors there.
please edit the php.ini file by using the sudo gedit /etc/php5/apache2/php.ini and on the Production Value,or you can also use the ini_set('display_errors', '1'); at the top of your php file
I had the same problem but unrelated with php.iniif you have same error, before you begin snipping on your server, first check your code.Mistake can be a missing } ) or ; or something like that.this is just reference what to do first.