I recently updated my linux mint via the automatic updater. I had the problem, that it did not execute php scripts. After re-installing libapache-mod-php5 some php started to work. Yes, just some, as phpinfo() is executing properly, but another php file, which works correctly on other machines, and was working on mine too, is now producing the following error in resopnse to an $.ajax call: status: parsererror errSyntaxError: Unexpected token <. what happens is it returns the php file without executing it, even though it executes other php files.
My configs are the following:
Server version: Apache/2.4.6 (Ubuntu)
PHP 5.5.1-1~precise+1 (cli) (built: Jul 22 2013 07:33:14)
Copyright (c) 1997-2013 The PHP Group
Zend Engine v2.5.0, Copyright (c) 1998-2013 Zend Technologies
with Zend OPcache v7.0.2-dev, Copyright (c) 1999-2013, by Zend Technologies
The problem was that after the update the php.ini got overwritten and it was not interpreting shortcode. The solution is to set
short_open_tag=On
in the php.ini as suggested here.