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.
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.
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 their is no correct index page to load.
The error could be caused by our mod_security rules. Please contact us for further help.
Protect against common file injection attacks” Blocks the component from functioning properly
1. Go into Admintools HTAccess Maker and disable “Protect against common file injection attacks”
2. Go into Global Configuration under the Server tab and set Error Reporting to NONE.