Blog · Sep 12, 2026
The 5 most common reasons a site can't be scanned
22.3% of the sites we tried to scan failed. Five causes account for more than 70% of those failures.
Key takeaways
- 2,973 of 13,342 attempted sites (22.3%) couldn't be scored.
- The top five causes (connection errors, 403, 401, 404 and timeouts) account for 2,117 failures (71%).
- A scan failure doesn't prove AI crawlers fail too, but it is worth treating as a warning sign.
1. Connection errors (1,116 sites)
What it means: the scanner couldn't reach the server at all, like calling a disconnected number. Causes include expired domains, DNS problems, lapsed hosting, a firewall that silently drops connections, or a server that is down.
How common: the largest group, at more than a third of all failures. Some of these sites may simply be abandoned: a domain still registered with nothing behind it.
The fix: confirm your domain is registered and your hosting is active and paid. If the site loads for you but not for others, ask your host whether a firewall is dropping unfamiliar visitors.
2. 403 Forbidden (449 sites)
What it means: the server saw the request and refused it, usually because of a firewall, security plugin or bot-blocking rule.
The fix: review your security plugin and firewall allowlists, and make sure legitimate crawlers aren't treated as attackers. Our post on sites that refused our scanner has the full checklist.
3. 401 Unauthorized (303 sites)
What it means: the site asked for a login before showing anything, sometimes across the whole site. This is often a membership, coming-soon or maintenance plugin left running on a live site.
The fix: check for plugins walling off public pages. Your homepage, services, about and contact pages shouldn't require a login.
4. 404 Not Found (126 sites)
What it means: the address we tried doesn't exist. The business may have changed domains or restructured its site without redirects.
The fix: after any move or redesign, set up 301 redirects from old URLs to new ones instead of deleting pages, and make sure the address you promote on Google, social media and print is the one that's live.
5. Timeouts (123 sites)
What it means: the server started to respond and never finished, so the scanner stopped waiting. This is usually an overloaded or misconfigured server. A patient human might eventually see the page, but automated visitors work to time limits.
The fix: ask your host about server response times, turn on caching (most WordPress caching plugins help), remove resource-heavy plugins, and consider whether your hosting plan has been outgrown.
Why this matters for AI visibility
We can say what happened to our scanner. We can't say for certain what each AI crawler experiences, since crawlers differ in how long they wait and how they identify themselves. But the causes above are problems for any automated visitor, and a site that can't be reached, refuses visitors, or answers too slowly gives AI crawlers little to work with. Your site has two audiences now, people and machines, and most owners only test the first.
What to do
- Run a scan. If it completes, you're past the biggest hurdle and can work through the findings.
- If it fails, the error tells you which of the five you're dealing with.
- Apply the matching fix, then re-scan to confirm.
About this data: 13,342 sites attempted in October 2026; 2,973 (22.3%) could not be scored. Remaining failures (856) include SSL errors, rate limits and other errors.