The top reasons for this error are permissions or .htaccess error.
The 403 Forbidden error means that your file has bad permissions. Directories and folders must be 755. Executable scripts within the cgi-bin folder must be 755. Images, media, and text files like HTML should be 755 or 644.
Hidden files (dot files)
If you see "client denied by server configuration" in your Error Logs, then this usually means bad file permissions, but could also mean that the visitor is trying to look at a hidden file, like the .htaccess file. You cannot look at that file in your browser or any file name that starts with a dot.
e.g. http://domain.com/.htaccess will always result in a 403 error.
The account may have IP Deny rules. Check in cPanel and make sure you are not blocking your own connecting IP.
You may have changed the Index Manager to No Indexing. This will cause a 403 error if there is no correct index page to load.
The error could be caused by our mod_security rules.