Error 1003 appears when someone browses directly to a Cloudflare IP address in their browser instead of using a hostname. Cloudflare's reverse proxy requires a valid Host header with a domain name to determine which origin to route the request to. Direct IP access provides no hostname, so Cloudflare cannot route the request. This is normal behavior and not an indication of a problem with your site.
Someone typed a Cloudflare edge IP address into their browser URL bar. Since no hostname is provided, Cloudflare does not know which site to serve.
Automated scanners often probe IP addresses directly. This error prevents them from accessing any site behind Cloudflare without knowing the hostname.
An application or script is sending HTTP requests to the Cloudflare IP rather than the domain name, missing the proper Host header.
Access the site using its domain name (e.g., example.com) rather than the IP address. Cloudflare requires a hostname to route requests.
If an application is making requests by IP, update it to use the domain name and include the correct Host header.
If you see this in analytics, it is likely from automated scanners. This is expected behavior and does not affect legitimate visitors.
A DNS record points to an IP address that Cloudflare has blocked for policy or security reasons.
Cloudflare's DNS could not resolve the requested hostname.
The DNS record resolves to an IP address that Cloudflare restricts for the current plan or configuration.