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First decide which crawler you want to allow
“AI crawlers” are not one interchangeable group. Decide which operator’s crawler is failing and what access you intend to permit. For OpenAI, OAI-SearchBot and GPTBot have separate robots.txt controls: search visibility and model-training access are distinct choices. Allow only the access that matches your intent; don’t assume a rule for one bot covers every purpose.
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This is a general troubleshooting guide, not a diagnosis of any particular website. Identifying the cause on your site requires its URL, configuration and request logs.
Check the robots.txt file the crawler actually receives
Fetch /robots.txt from the exact hostname serving the affected page, including the relevant subdomain. Inspect its status, any redirects, and the rules for the crawler and path in question. The origin file may not be the effective file: a CDN can prepend managed rules or serve its own robots.txt. Cloudflare, for example, documents that its managed robots.txt can add rules to an existing file and can be generated when a site has no file: Cloudflare Managed Robots.txt.
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Robots.txt is a policy file, not a way to repair a blocked network request or a server error. Google’s documentation explains how crawlers handle robots.txt status codes and redirects; inability to retrieve the file can affect crawling too: Google’s robots.txt specifications.
- Confirm you fetched the file from the same host as the page, not a different domain or staging environment.
- Check that the relevant user-agent group and path rules don’t disallow the target URL.
- Check whether a redirect, error response or CDN-managed rule changes what the crawler receives.
- Avoid pasting in a blanket allow-all policy before deciding which crawler purposes you want to support.
Inspect the affected page’s status and body
Request the exact page URL and examine both its HTTP status and the content returned. A crawler may be permitted by robots.txt but receive a 403, CAPTCHA, JavaScript challenge, login screen, geographic restriction or server error. OpenAI’s crawler guidance identifies these protections and successful page responses as relevant checks: OpenAI crawler guidance.
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Look at the body, not just the status code. A nominally successful response that contains a challenge, sign-in page or error template is not the page content you intend the crawler to read. If you test from a browser, remember that its result may differ from the response to the crawler’s request.
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Use the request time, path, response status and available crawler identification to compare CDN/WAF events with origin and application logs. Check both edge rules and origin-level anti-bot modules; a request that passes one layer may be denied by another.
For a proxied site, compare the response through the CDN with direct-origin monitoring where your setup permits it. Cloudflare’s troubleshooting guidance says 5xx responses indicate an internal error at Cloudflare or the origin, and recommends checking anti-bot modules and monitoring through Cloudflare and directly to the origin: Cloudflare 5xx troubleshooting. Use the logs and comparison to locate the failing layer before changing security settings.
| What you observe | Likely area to investigate | Next check |
|---|---|---|
| Robots.txt disallows the crawler or path | Origin robots.txt or CDN-managed robots rules | Inspect the effective file served for the exact hostname and adjust only the relevant rule. |
| 403, challenge, CAPTCHA or login page | CDN/WAF, bot mitigation, origin module or authentication | Match the request to edge and origin logs; identify which control generated the response. |
| 5xx response | CDN or origin server | Compare proxied and direct-origin behavior and inspect the corresponding logs. |
| Success status but unexpected body | Application, challenge flow, geographic rule or page delivery | Check whether the returned content is the intended page rather than an interstitial or error template. |
Verify crawler identity before changing allowlists
Use the operator’s current documentation and your provider’s maintained bot reference to identify the crawler and available verification methods. A user-agent string can help filter logs or match a supported rule, but the string alone does not authenticate a request. Cloudflare maintains a reference to recognized bots and detection information: Cloudflare verified bots. Check current operator and platform documentation while implementing because bot names and verification methods can change.
Quick Recap
Make one targeted change, then retest
- Record the baseline. Note the crawler, affected URL, time, robots.txt response, page status and returned body.
- Identify the blocking layer. Use CDN/WAF events and origin or application logs to determine which rule or component produced the response.
- Change that control only. If robots.txt is the issue, adjust the relevant crawler and path rule. If a WAF or anti-bot module is responsible, narrowly permit the intended verified traffic where the provider supports it. Don’t disable protections broadly to test a hunch.
- Request the same URL again. Check both the HTTP status and whether the body now contains the intended page, rather than a challenge, login screen or error.
- Confirm the request in logs. Verify that it reached the expected layer and was handled by the rule you changed. If it still fails, return to the next layer instead of changing multiple controls at once.
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