HTTP 404 - Cause
The 404 (Not Found) status code indicates that the URL or path requested could not be found on the target server, or that it internally points to the wrong resource (redirect / proxy).
Solution/Troubleshooting
First, check the URL or path you have entered; if this is correct, it may help to clear your browser’s cache and cookies to remove any faulty redirects from the cache. If this does not resolve the issue, you will need to contact the website operator or check your error logs on the server, provided it is your own website.
The following article may be helpful in this regard: How do I read my log files?