Google Ad Manager crawler errors can prevent publishers from getting the expected advertising coverage on their websites. Even when a page loads normally in your browser, Google’s ads crawler may be unable to access its content because of robots.txt rules, login restrictions, server responses, redirects, or other access problems.

These issues can affect how Google understands a page and which ads it can serve. For publishers troubleshooting site approval or unexpected ad-serving problems, checking crawler access is an important diagnostic step.

This guide explains how the Google Ad Manager ads crawler works, how to inspect your robots.txt file, how to investigate access errors, and what to check after making a fix.

What Is the Google Ad Manager Crawler?

The Google Ad Manager ads crawler visits webpages to understand their content and help determine relevant advertising. It may access URLs on which Google ad tags are implemented, including pages that redirect.

When the crawler cannot access a page’s content, Google may have difficulty determining relevant ads for that page. Depending on the circumstances, this can affect ad relevance, coverage, or revenue.

A crawler access issue is not automatically a policy violation or a site disapproval. These are separate issues that need to be diagnosed using the status and error information shown in your account.

Read Google’s official About the Ad Manager crawler documentation for more information about its behavior.

Common Google Ad Manager Crawler Errors

1. Check Your robots.txt File

The robots.txt file contains rules that tell supported crawlers which URLs they may request. A rule intended for a particular bot can unintentionally block the Google Ad Manager ads crawler.

Step 1: Open your robots.txt URL

Visit the robots.txt file at the root of the domain serving the affected webpage. For example, if your website is example.com, open:

Replace example.com with your actual domain. If your site uses both www and non-www hostnames, redirects, or separate subdomains, check the hostname that is actually serving the page.

Step 2: Look for the ads crawler’s user-agent rules

Search the file for a section that names Mediapartners-Google. For example, the following rules explicitly block that crawler from the entire site:

Google specifically identifies these rules as a cause of ads-crawler access problems. If they are present and you want the crawler to access those pages, remove or correct the blocking rules.

Do not blindly delete every Disallow directive in your robots.txt file. Review which user-agent group the rule belongs to and which paths it affects. Other rules may be intentionally protecting private or non-public areas of your website.

Step 3: Check whether the relevant path is blocked

Inspect the complete robots.txt file, including rules for individual user agents and wildcard groups. Check whether the affected URL’s path is blocked under the rules applicable to the ads crawler.

One important nuance: Google documents that the Ad Manager crawler may still crawl pages blocked by a general User-agent: * rule. A rule specifically targeting Mediapartners-Google can have a different effect. Therefore, do not assume that every wildcard Disallow rule is the cause; inspect the actual directives and the error reported by Ad Manager.

See Google’s official guide: Troubleshoot Ad Manager crawler errors .

2. Check Whether the Website Is Accessible

If robots.txt allows access, check whether the page is reachable without authentication and whether the server returns an appropriate response. A page that loads on your own computer might still be unavailable to an external crawler.

1. Open the exact affected URL in a private or incognito browser window.
2. Check whether it loads without requiring a login or manual interaction.
3. Confirm that the URL does not redirect to an unrelated page, an error screen, or an inaccessible destination.
4. Check whether your hosting provider, CDN, firewall, or security plugin blocks automated requests.
5. Ask your hosting provider to inspect server access logs if Ad Manager reports that the site is unavailable.

Where you have access to a terminal, a basic request can help check the response returned by the server:

Replace the example URL with the affected page. This command follows redirects and displays response headers. It is a basic diagnostic only: it does not reproduce every request made by Google’s crawler, and a successful response does not prove that the ads crawler can access the page.

3. Check Firewall, CDN, and Bot Protection Rules

Security systems can sometimes block automated requests even when the website is available to ordinary visitors. This can happen because of bot-protection settings, IP restrictions, rate limits, geographic restrictions, or rules that challenge suspicious traffic.

Ask your developer or hosting provider to investigate:

• HTTP 403 Forbidden responses that indicate an access restriction.
• HTTP 429 responses caused by rate limiting.
• HTTP 5xx errors or timeouts returned by the origin server or CDN.
• Security challenges that require JavaScript execution or human verification.
• Geofencing rules that prevent access from certain locations.
• Rules that block automated requests based only on an unverified user-agent string.

Use server and security logs to identify the actual blocked request. Do not broadly disable your firewall or allowlist IP addresses based solely on a user-agent string. Verify crawler identity using Google’s published guidance and work with your security provider to make the narrowest appropriate change.

4. Configure Access for Login-Protected Pages

If the page requires a username and password, the ads crawler may not be able to reach its content without an appropriate crawler-login configuration.

Google Ad Manager supports crawler access settings for eligible login-protected content. The setup generally involves configuring the login information in Ad Manager and verifying the relevant site through Google Search Console.

Where to find crawler access settings

1. Sign in to Google Ad Manager.
2. Open Admin → Access & authorization → Crawler access, where available in your account.
3. Select the option to add a new login.
4. Enter the restricted URL or directory, login URL, authentication method, and the required login parameters.
5. Follow Google’s site-verification instructions and test the setup.

Not every authentication system will work with the supported setup. Review Google’s instructions before changing a login system or exposing restricted content.

Official guide: Display ads on login-protected pages .

5. Investigate Redirects and URL Variations

Google may crawl the original URL as well as the destination when a page redirects. An error on the original URL or any part of the redirect path can prevent the crawler from reaching the intended content.

Check for the following:

• HTTP-to-HTTPS redirects that fail or loop.
• Redirects between www and non-www hostnames.
• Redirects to pages that require a login or return an error.
• Long redirect chains that introduce unnecessary requests.
• Different behavior for URLs with trailing slashes or query parameters.

Test the original URL and the final destination individually. If the server returns an error, ask your developer to correct the redirect or access issue rather than repeatedly resubmitting the same URL.

6. Do Not Confuse Crawler Errors With ads.txt Problems

The ads.txt file and the webpage’s content crawler serve different purposes. The crawler accesses page content, while ads.txt helps advertising systems verify authorized digital sellers.

If Ad Manager reports an ads.txt problem, check the ads.txt file separately. Make sure it is available at the correct hostname, returns the expected text, and is not blocked by robots.txt, redirects, or server restrictions.

For example, a basic check is:

Open the URL and confirm that the file returns the expected content instead of an error page or unrelated HTML. If the website uses multiple hostnames, verify which hostname Ad Manager expects for the domain.

Follow Google’s ads.txt and app-ads.txt crawler access guide for the specific requirements.

7. What to Do After Fixing a Crawler Error

Correcting robots.txt or server access rules does not necessarily update Google’s crawler information immediately. Google explains that changes may not be reflected until its crawler visits the site again.

After making a change:

1. Confirm that the updated robots.txt file is publicly accessible.
2. Verify that the affected URL loads and returns the expected response.
3. Check that caching layers or CDN rules are not still serving an old robots.txt file or blocking the request.
4. Review Ad Manager’s crawler access diagnostics and any associated site-status messages.
5. Allow time for the automated crawler to revisit the page.
6. Recheck the status before making further changes.

You generally cannot force the Ad Manager ads crawler to visit a particular page immediately. Avoid repeatedly changing robots.txt rules or resubmitting a page without new evidence of a remaining problem.

8. Does a Google Ad Manager Crawler Error Affect Google Search Rankings?

A Google Ad Manager ads-crawler error is not the same as a Google Search crawling or indexing error. Fixing an ads-crawler issue does not, by itself, guarantee improved organic rankings.

If you are also experiencing Google Search indexing problems, investigate those separately in Google Search Console. Check the affected URL, indexing status, server availability, and the rules applicable to Googlebot.

Google’s documentation explains the difference between crawling and indexing in its Google Search crawling troubleshooting guide .

Quick Google Ad Manager Crawler Troubleshooting Checklist

• Open the affected page’s robots.txt file.
• Check for rules that explicitly block Mediapartners-Google.
• Confirm that the affected page is publicly accessible when intended.
• Check HTTP status codes, redirect chains, and server availability.
• Review CDN, firewall, bot-protection, and geofencing rules.
• Configure supported crawler login access for eligible protected pages.
• Investigate ads.txt separately if the reported issue concerns authorized sellers.
• Review the exact crawler or site error reported by Ad Manager.
• Allow the crawler time to revisit the page after the fix.

Frequently Asked Questions

What is the Google Ad Manager crawler called?

The Ad Manager ads crawler commonly uses the user-agent name Mediapartners-Google. Check Google’s current documentation for details about the crawler and its behavior.

Can robots.txt prevent Google Ad Manager from serving ads?

Yes. If robots.txt explicitly blocks the Ad Manager ads crawler from accessing a page, Google may be unable to crawl that page’s content for advertising purposes. Review the rules applicable to the crawler and remove unintended restrictions.

My website works normally. Why does Ad Manager say it is unavailable?

Your browser and Google’s crawler may receive different responses. Firewall rules, rate limits, server errors, geofencing, authentication, or redirects can prevent crawler access even when the page works for you. Review server logs and security settings to find the cause.

How long does it take Google to recrawl a page after a fix?

Recrawling is automated, and the timing is not guaranteed. Google says changes to crawler-access conditions may take time to be reflected after its crawler revisits the site. Monitor the status instead of assuming that a successful configuration change will update the account immediately.

Does fixing a crawler error automatically approve a disapproved website?

No. A crawler error and a site disapproval are different issues. Correcting crawler access may resolve an access-related problem, but any separate site-review or policy issue must be addressed using the instructions shown in Google Ad Manager.

Google Ad Manager crawler errors should be diagnosed by checking the exact reported issue, robots.txt directives, page accessibility, server responses, and authentication requirements. Correct the specific cause, verify the result, and allow time for the ads crawler to revisit the affected page.

Last reviewed: October 2026. Google Ad Manager interfaces and crawler behavior may change. Refer to the official Google documentation linked throughout this guide for current instructions.