This error occurs when you have a tried to reach a (sub)domain that doesn’t exist, or at least that your machine cannot find. This is essentially a DNS problem that can be caused by:
- A typo in the domain part of the URL
- A record that is missing for that domain
- The nameserver queried (or more precisely, the resolver of your machine) fails to resolve the record to an IP address
Fixing the first point is obvious, and the last point happens rarely. The most common situation for this to happen is that the record (for instance, the “www” bit of http://www.example.com/) that you tried to reach is missing in the DNS settings of your account*. Visit the “DNS” section of your account to add the missing record. Please note that if you want your visitor to be able to reach your website via http://example.com, you also need to create a record for example.com too, even if they are redirected to http://www.example.com immediately after.
* or on the authoritative name server, if your domain is a CNAME setup (Full setup versus Partial CNAME setup) Note that if the record exists on the authoritative nameserver but not in your Cloudflare account DNS settings, another kind of error appears: Error 1001 DNS resolution error.