A Directory Listing Denied error is generated when there is no Index file in the requested directory.
The index file automatically displays when a browser requests the directory on a website. They are most commonly named index.php, index.html, Default.asp, Default.aspx, and index.htm. If you see this error displayed on your recently updated or recently uploaded site, it means there is no index file matching the preconfigured list of valid index files for the webserver. In this instance, you are encouraged to rename the web page you would like to display as the default to one of the previously listed filenames.
With each newly created account, a standard Index file named index.htm is installed into the root directory. If you name your home page index.html, the pre-installed file, index.htm, should be deleted or taken off the server. Even with the presence of a home page named index.html, the .htm version has priority.