What does Google say about SEO? /

Official statement

Completely blocking a folder with robots.txt prevents Google from knowing the content of the pages. If external links point to these blocked pages, Google cannot indirectly transfer those links to the main content. It is essential to avoid blocking important pages that receive links.
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Extracted from a Google Search Central video

⏱ 1h14 💬 EN 📅 11/12/2020 ✂ 46 statements
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Other statements from this video 45
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📅
Official statement from (5 years ago)
TL;DR

Blocking an entire directory with robots.txt prevents Google from crawling its content, but also from redistributing the SEO juice from backlinks pointing to those blocked pages. In practical terms, if external links point to /old-folder/ and you block that path, Google cannot follow internal redirects or transfer that authority to your active pages. Avoid blocking URLs that receive quality backlinks — prefer 301 redirects to preserve value transfer.

What you need to understand

Why does blocking a folder cut off the incoming PageRank flow?

When you add a Disallow directive in your robots.txt to block an entire directory, Google can no longer access the content of those pages. The bot stops at the door.

The problem is that Google does not recognize internal redirects or outgoing links from these blocked pages. If an external backlink points to /blog-archive/article-123, and you block /blog-archive/, Google sees the incoming link but cannot follow the 301 redirect that you may have set up to /blog/article-123.

How does Google handle backlinks to blocked URLs?

Google considers these backlinks as orphan signals: it knows they exist, but it cannot leverage them to strengthen the authority of your active pages. The theoretical PageRank remains stuck at the entry.

Unlike a 404 or 410 page that Googlebot can crawl and identify redirects from, a URL blocked by robots.txt remains a black box. No content discovery, no juice transmission.

What's the difference with an indexed but empty or removed page?

If you leave a page accessible but empty (or 404), Google can at least crawl the page, detect a possible 301 redirect, and follow the trail to the new target URL. The PageRank transfer occurs normally then.

With robots.txt, you cut off any exploration. Google never sees the HTTP response code, nor the redirect headers. It's like denying access to a warehouse: delivery trucks (backlinks) arrive, but no one knows where to unload the goods.

  • Blocking with robots.txt = Google does not crawl, does not see redirects, does not transfer the PageRank from incoming backlinks
  • 404/410 crawlable = Google crawls, detects the disappearance, can follow a possible 301 redirect and transfer authority
  • Direct 301 redirect = Google follows the redirect, transfers PageRank to the new target URL without major loss
  • Never block a folder that receives quality backlinks without first verifying that no redirects need to be crawled
  • Use robots.txt only to protect sensitive content, internal duplicate or unnecessary crawl budget — never to manage migrations or URL restructurings

SEO Expert opinion

Is this statement consistent with field observations?

Yes, and it's an official confirmation of what many SEO practitioners have already been doing for years. Blocking a complete directory with robots.txt to "clean up" a site is a classic mistake among beginners or sloppy SEO audits.

I have seen sites lose 30 to 40% of their organic traffic after blocking /blog/ or /resources/ because a developer wanted to "hide outdated content". The backlinks were still there, but Google could no longer leverage them. [To be verified]: Google does not publish figures on the percentage of PageRank lost in this scenario, but the impact is practically measurable.

What nuances should be added to this rule?

The indirect transfer that Mueller talks about concerns internal links from blocked pages to active pages. If you block /old-site/ which contained links to /new-site/, Google never sees these internal links and cannot distribute PageRank accordingly.

But be careful: blocking in robots.txt does not always prevent indexing. Google can index a blocked URL if it receives backlinks, even without crawling the content — you will then see an empty snippet in the SERPs. This is counterproductive: the URL clutters the index without adding value, and the PageRank remains stuck.

In what cases does robots.txt remain relevant for blocking a folder?

Blocking with robots.txt makes sense to protect technical content: /wp-admin/, /cgi-bin/, /scripts/, /tmp/. These folders normally do not receive any external backlinks and should not appear in the index.

Also useful to save crawl budget on infinitely paginated pages, redundant facet filters, or automatically generated parameterized URLs. But in these cases, always check that no backlinks point to these paths before blocking.

Attention: If you are migrating a site and blocking the old domain or folder via robots.txt, Google will never be able to crawl your 301 redirects. The result: a loss of PageRank. Always leave the old URLs accessible while Google follows all the redirects.

Practical impact and recommendations

What should you do if you've already blocked a folder that receives backlinks?

Immediately remove the Disallow directive from the robots.txt file for that directory. Google will then be able to crawl the pages, discover your 301 redirects, and transfer PageRank to the new target URLs.

Check in Google Search Console (Coverage or Indexed Pages section) if blocked URLs appear with the status "Blocked by robots.txt". If so, unblock and submit a new validation to accelerate the re-crawl.

How to audit your robots.txt to identify risky blockages?

Export your backlink profile from Ahrefs, Majestic, or SEMrush. Cross-reference these URLs with the blocked paths in your robots.txt. Any overlap is a red flag.

Use a Python script or spreadsheet to spot patterns: if /resources/ is blocked but receives 150 backlinks from referring domains, you are likely losing PageRank. The same logic applies to old blog URLs, archived landing pages, or past campaigns.

What strategy should be adopted to restructure a site without losing SEO juice?

Never block a folder before you have implemented clean 301 redirects and verified that they work. Allow Google to crawl these redirects for at least 3 to 6 months so it can transfer PageRank.

If you must absolutely remove content from the index, use the noindex tag instead of robots.txt: Google will be able to crawl, see the directive, and properly de-index without cutting off the link flow. Once de-indexed, you may consider blocking if crawl budget is a concern.

  • Audit robots.txt and cross-reference with backlink profile to identify problematic blockages
  • Remove any Disallow directive on folders receiving quality external links
  • Implement permanent 301 redirects before any URL restructuring or migration
  • Keep old URLs accessible and crawlable for at least 6 months after migration
  • Use noindex instead of robots.txt to remove content from the index without cutting off PageRank transfer
  • Monitor Google Search Console to detect blocked URLs that still appear in the index
Blocking a folder with robots.txt cuts off the PageRank transfer from incoming backlinks to your active pages. Always prefer crawlable 301 redirects to preserve authority. Regularly audit your robots.txt file to avoid blocking strategic URLs. These technical optimizations — proper migration, fine management of crawl budget, preservation of link equity — require sharp expertise and constant vigilance. If you lack internal resources or your site has already experienced unexplained traffic losses, support from a specialized SEO agency can help you diagnose hidden blockages and orchestrate a seamless redesign.

❓ Frequently Asked Questions

Peut-on perdre du PageRank en bloquant un dossier avec robots.txt même si on a mis des redirections 301 ?
Oui, car Google ne peut pas crawler les redirections si le dossier est bloqué. Le bot s'arrête avant de voir les en-têtes HTTP 301, donc le PageRank des backlinks entrants ne se transfère jamais vers les nouvelles URLs.
Quelle différence entre bloquer avec robots.txt et désindexer avec noindex ?
Robots.txt empêche le crawl : Google ne voit jamais le contenu ni les redirections. Noindex permet le crawl mais demande la désindexation : Google peut suivre les redirections et transférer le PageRank avant de retirer la page de l'index.
Combien de temps faut-il laisser les anciennes URLs accessibles après une migration ?
Au minimum 6 mois, idéalement 12 mois. Cela laisse à Google le temps de crawler toutes les redirections 301, de transférer le PageRank, et de mettre à jour son index. Ne bloquez jamais avant cette période.
Google peut-il indexer une URL bloquée par robots.txt si elle reçoit des backlinks ?
Oui, Google peut indexer l'URL sans crawler le contenu, affichant une snippet vide dans les résultats. Cela pollue l'index et bloque le transfert de PageRank — exactement ce qu'il faut éviter.
Quel impact sur le crawl budget si on débloque un gros dossier bloqué depuis longtemps ?
Google va probablement crawler massivement ce dossier pour rattraper le retard. Surveillez les logs serveur et Google Search Console. Si le crawl budget explose, utilisez des paramètres URL ou des balises canoniques pour guider Googlebot vers les pages prioritaires.
🏷 Related Topics
Domain Age & History Content Crawl & Indexing Links & Backlinks

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