*** SECURITY REQUIREMENT ***
For added security, Zen Cart™ comes with several .htaccess files already included in various folders to help provide protection against unwanted visitors and even against mis-use of your site in the unfortunate situation of your site being hacked. These protections prevent hackers from using your site as phishing sources.
However, for these built-in protections to work, your web hosting server administrator MUST set the AllowOverride directive in the server's apache configuration (the server's master httpd.conf file) to "All" or at least ensure it includes these parameters: 'Limit Indexes'.
Code:
ie: AllowOverride All
or: AllowOverride Limit Indexes
(NOTE: You must also add "Options" if uncommenting OPTIONS directives in your .htaccess files)
Without these settings, you will likely encounter "500 Internal Server Error" messages when attempting to access various parts of your site, including perhaps the zc_install installer script.
Storeowners hosting on Windows Servers using IIS instead of Apache may need to remove the .htaccess files and rework them into suitable equivalents within your IIS configuration. See Microsoft's IIS website for specific assistance.
ADDITIONAL NOTE ABOUT .htaccess FILES
Inside some folders is an .htaccess file that lists certain *permitted* filetypes which may be accessed. (Anything else is blocked to prevent abuse on your site).
The side-effect of this is that if you choose to use media types that are not already listed in the *permitted* list, then your visitors will not be able to see those resources.
Thus, if you are using product images that are not in the list of permitted types in your /images/.htaccess, you will need to add those types to the list.
Similarly, if you are using certain media types in music product previews, you will need to make sure those are in your /media/.htaccess
And, if you are using filetypes for downloadable products that are not already listed in your /pub/.htaccess and /download/.htaccess you will need to add those as well.