Symptoms

When access a protected directory, login/password is not asked, only error is shown:

403 Directory index forbidden

Also, this error may occur if you access not protected but the regular directory.

Cause

Directory index forbidden error occurs if there is no index file in the directory and directory indexing is disabled in Apache configuration.

Resolution

To avoid this error the index file should be put into the directory. Index file's extensions are defined in httpd.conf by means of DirectoryIndex directive, for example:

 DirectoryIndex at_domains_index.html index.html index.html.var index.shtml index.php index.htm

Or enable directory indexing with Options +Indexes directive for the domain by means of vhost.conf or for the whole server in httpd.conf

Restart Apache if you changed any configuration file.

Check apache.org/#directoryindex and apache.org/#options for more details.