Here's a quick explanation on what some of our server alerts and errors mean.
The 403 error is the ‘Forbidden’ error. It’s triggered when website or file settings have been configured with permissions above what users or the scanner is able to view the site with. This can be seen sometimes when a site has been suspended by the host. We are able to clean sites when they are in this status, as long as we have server access.
A 404 error is a ‘Not Found’ error. It means that whatever is being looked for, doesn’t exist. Websites often have a special page that shows up if a user tries to access a random page on the site that isn’t there. Hackers often attack and infect the 404 page. So if you see an alert for a 404errorpage, that’s because we are seeing a problem with the 404 page being used on the site that was scanned. This may be an indication of malware, so be sure to double-check.
A 500 error is a server error. It means that there are problems in the backend code that controls the website. There are several things that can cause it, and malware is commonly one of them but it can also be just a temporary hosting error
503 error - Unable to properly scan your site. Unable to connect
This message can appear for a couple of reasons. If the website is offline, and rejecting certain types of requests, then this can cause SiteCheck to return this error. If the site is up and running, but we can’t scan it, then website is using some method to block certain user agents or requests from being sent to the site. This can be a result of security software, manually placed blocking scripts, or even malware.
What to do if you receive an alert
In most cases, you'll need to check with your host regarding server errors.
If you are still not sure what do, please feel free to open a support ticket with the Sucuri team.