What does Google say about SEO? /

Official statement

SEO expert Glenn Gabe indicated on Twitter that, in Search Console, if URL A redirects to URL B which is blocked by robots.txt, URL A will be marked as also blocked by this file, even though, in reality, this is not the case. John Mueller had explained this in a hangout last year.
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Official statement from (5 years ago)

What you need to understand

What happens when a redirect points to a blocked URL?

Google has revealed a peculiar behavior in Search Console regarding redirects. When URL A redirects to URL B which is blocked by the robots.txt file, Search Console displays URL A as being blocked as well.

This indication is misleading because technically, URL A is not directly blocked by robots.txt. It's only its final destination that is. This confusion can generate erroneous alerts in your reports.

Why does Google display this information in such a confusing way?

Google simplifies the message by indicating that the source URL is blocked, when in reality it's the redirect chain that leads to a dead end. This simplification likely aims to alert webmasters to an accessibility issue.

The problem becomes particularly thorny on old and large sites with a complex history of redirects. Identifying the true source of the blockage can become a real headache.

What are the essential takeaways from this statement?

  • Search Console marks a URL as blocked if its redirect destination is blocked by robots.txt
  • The source URL is not technically blocked itself, it's a misleading display
  • This behavior can create confusion in crawl error analysis
  • Sites with a complex history are particularly affected by this display ambiguity
  • Google acknowledges the issue and might correct the interface in the future

SEO Expert opinion

Does this statement align with practices observed in the field?

Absolutely. This situation is frequently encountered during technical SEO audits, particularly after migrations or site restructurings. Teams end up with blocking alerts in Search Console without immediately understanding why.

The problem is amplified by the fact that many sites maintain successive layers of redirects over the years. One redirect can point to another redirect, which itself leads to a blocked URL, creating a true diagnostic labyrinth.

What nuances should be brought to this information?

It's crucial to understand that this is not a Google bug, but an interface choice. Google follows the redirect chain and finds that it leads to a dead end. From a crawl perspective, the result is identical: the page is not indexable.

The important nuance concerns report interpretation. When you see a URL marked as blocked, you must systematically check whether it's a direct block or a block via redirect. This distinction radically changes the corrective action to take.

Warning: Don't just unblock the source URL in robots.txt. This won't solve anything if the final destination remains blocked. You need to trace back the entire redirect chain to identify the real problem.

In what cases does this situation cause the most problems?

E-commerce sites and large media portals are particularly vulnerable. They often accumulate thousands of redirects following catalog changes, taxonomy updates, or editorial structure modifications.

Poorly managed domain migrations also create this type of situation. If the old domain redirects to the new one, but certain sections of the new site are blocked, you get this massive false positive in Search Console.

Practical impact and recommendations

How do you properly diagnose this type of problem?

Start by manually tracing the redirect chain. Use tools like Screaming Frog, Chrome extensions for checking redirects, or simply curl command line to follow the complete journey.

Then check your robots.txt file to identify which rule precisely blocks the final URL. Sometimes, it's an overly broad generic rule that unintentionally blocks important sections.

What corrective actions should be implemented?

The first step is to clean up unnecessary redirects. If URL A redirects to B which is blocked, ask yourself if this redirect is still relevant. Perhaps it should point elsewhere or be removed.

Next, review your robots.txt strategy. Are all the blocks intentional and necessary? Some old rules may be obsolete and cause more problems than they solve.

What methodology should you adopt to avoid these situations in the future?

  • Systematically document your robots.txt rules with comments explaining their rationale
  • Maintain an inventory of main redirects, especially after each migration or redesign
  • Always test a redirect end-to-end before putting it into production
  • Regularly audit redirect chains to avoid unnecessary cascades
  • Set up alerts in Search Console to quickly detect new blocks
  • Favor direct redirects rather than multiple chains
  • Review your robots.txt with each structural modification of the site

In summary: The confusion created by Search Console's display requires heightened vigilance in analyzing crawl reports. Adopt a methodical diagnostic approach by systematically tracing back redirect chains.

Prevention remains the best strategy: maintain a clean redirect architecture and a documented robots.txt. For complex sites with a heavy technical history, these optimizations can quickly become time-consuming and require specialized expertise. Engaging a specialized SEO agency allows you to benefit from personalized support to untangle these complex situations, implement best practices, and avoid the technical pitfalls that penalize your visibility.

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