This error can be caused by the following reasons:

1.) The file doesn't exist in the https directory. This can be verified by trying to get to the file using a regular, unsecure, http call, and seeing that the file is loaded correctly. In order to correct this problem please add the file to the https directory defined in the SSL configuration of the webserver.

2.) Port 443 is blocked by server's firewall or the end-user's firewall. In order to correct this, you must open up port 443 (for both inbound and outbound traffic) on the server's or user's firewall.

3.) The https server is down. Please ensure that the server running https services is up. This can be verified by checking your respective webserver task manager.

4.) Incomplete SSL certificate. In this particular case, it is possible that your SSL certificate does not have a corresponding private key file. Please reference the appropriate installation documents on our support site for your particular web server, and verify that you've installed the SSL certificate correctly by having the corresponding private key file.

5.) Web browser not set to 3.0. It is possible that the particular web browser needs to be set to 'Use SSL 3.0' in the relevant options menu.