Status code 0 is delivered to a user when there is no connection to retrieve the desired data from their requested URL.
Note that this is not an actual status code that a server will deliver, but it is the result of there being no connection to reach the server with, resulting in a timeout.
Timeouts can occur due to your network being down, the server not responding to a browser’s request, or a firewall access issue, amongst other things.
If you’re receiving a status code of 0 in your crawls or while attempting to find a web resource, check your network connection.
If there is a connection, look to see if there are security settings impeding your browser from connecting with the desired resource’s server, or any other potential impediments blocking the connection.
In some instances you may have a very slow network connection that is unable to handle the size of your requests, which can result in the 0 Status Code being returned as well.