Why does PHP stop recognizing $_GET variables?

Question

Something very odd has happened with a site/server that I do not have hosting access to.

I have a script that has been running for over 2 years. It has recognized $_GET vars from the URL address with no problems.

Now all of a sudden the script does not process any $_GET or $_REQUEST vars. I have made no changes to my PHP scripts since I launched them 2-3 years ago.

Does anyone know if there are recent server updates or PHP updates that can cause a working script to stop recognizing $_GET vars?

WordPress Plug-in script:

function email_this($data)
{
    global $post;
    if(isset($_GET['id']))//if it is a form
    { // 2014-05-03 SCRIPT DOES NOT FALL THROUGH HERE
        email_send(htmlspecialchars($_GET['id']));    
    }
    else//if the button should show
    { // 2014-05-03 SCRIPT FALLS THROUGH HERE
        $data_and_emailthis = $data; // 2011-03-23: split original statement into 2 statements
        $data_and_emailthis .= '<!--'; // 2011-03-23: added this to comment out ability to email articles from non-specified pages
        $data_and_emailthis .= '<br/><p><a href="/email/?id='.get_the_ID().'" rel="nofollow" title="Email this post to your friend" style="font-weight: bold;"><img src="'.get_bloginfo('wpurl').'/wp-content/plugins/emailthis/email.gif" style="border: 0px; padding: 0px; margin: 0px;" alt="Email this post"> Email this post</a></p>'; // 2011-03-23: split original statement into 2 statements
        $data_and_emailthis .= '-->'; // 2011-03-23: added this to comment out ability to email articles from non-specified pages
    }

  //return
  return $data_and_emailthis;
  }

add_filter('the_content', 'email_this');

URL:

http://mydomain.com/email/?id=1506

.htaccess file

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

<Files 403.shtml>
order allow,deny
allow from all
</Files>

deny from 41.207.163.6

Answer 1

I'm not sure how it was before, but to pass the query string, you need to modify:

RewriteRule . /index.php [L]

to:

RewriteRule . /index.php [L,QSA]

That way the query string gets appended after the url has been rewritten to index.php.