In zen cart getting 500 or 406 or 404 or 403 errors when submitting product updates in admin pages

Symptom:

When updating product details (or EZ-Pages content and other areas), when certain keywords are used in the content, an error message similar to the following may appear:

Forbidden - You don't have permission to access /admin/product.php on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.
Sometimes the error may appear as a "500 Internal Server Error" or "406" error etc.

Cause:

Many servers nowadays use a tool in their Apache Webserver software configuration called "mod_security" in order to prevent against hack attempts on the server.  This tool monitors the content of words/data submitted in forms on web pages, and if certain keywords are found, it flags the entire form-submission as at-risk, and prevents the entered data from being saved.

Common keywords which may get flagged include: INSERT or LYNX or UPDATE and other commonly-used SQL commands

Possible Solutions:

1. Don't use any words which are restricted by your host's rules.

2. Get your host to change or relax the mod_security rules.

3. You can try disabling mod_security for your admin area by putting this in your /admin/.htaccess file:

SecFilterInheritance Off

or this:

SecFilterScanPOST Off
If that doesn't work, you'll need to talk to your hosting company for specific assistance about ways in which *they* will allow you to override mod_security filters in your admin area.