Official statement
Other statements from this video 25 ▾
- □ Les liens JavaScript retardent-ils vraiment la découverte par Google ?
- □ Pourquoi Google ignore-t-il vos balises canoniques quand le HTML brut contredit le rendu ?
- □ Le noindex en HTML brut empêche-t-il définitivement le rendu JavaScript par Google ?
- □ JavaScript et SEO : peut-on vraiment modifier title, meta et liens côté client sans risque ?
- □ Le JavaScript côté client est-il vraiment un frein pour vos performances SEO ?
- □ HTML brut vs rendu : Google s'en fiche-t-il vraiment ?
- □ Google AdSense pénalise-t-il vraiment la vitesse de votre site comme n'importe quel script tiers ?
- □ Faut-il s'inquiéter des erreurs 'other error' sur les images dans la Search Console ?
- □ User agent ou viewport : quelle détection privilégier pour vos versions mobiles séparées ?
- □ Les liens de navigation JavaScript affectent-ils vraiment le référencement de votre site ?
- □ Peut-on vraiment perdre le contrôle de sa canonical en laissant l'attribut href vide au chargement ?
- □ Quel crawler Google utilise vraiment ses outils de test SEO ?
- □ Faut-il vraiment arrêter de craindre le JavaScript pour le SEO ?
- □ Les liens JavaScript retardent-ils vraiment la découverte par Google ?
- □ Pourquoi une balise canonical différente entre HTML brut et rendu peut-elle ruiner votre stratégie de canonicalisation ?
- □ Peut-on vraiment retirer un noindex via JavaScript sans risquer la désindexation ?
- □ Peut-on vraiment modifier les balises meta et les liens en JavaScript sans risque SEO ?
- □ Les produits Google bénéficient-ils d'un avantage SEO caché dans les résultats de recherche ?
- □ Faut-il s'inquiéter des erreurs 'other' dans l'outil d'inspection d'URL ?
- □ Google ignore-t-il vraiment vos images lors du rendu pour la recherche web ?
- □ User agent ou viewport : Google fait-il vraiment la différence pour l'indexation mobile ?
- □ Les liens générés en JavaScript transmettent-ils vraiment les signaux de ranking comme les liens HTML classiques ?
- □ Une balise canonical vide en HTML peut-elle forcer Google à auto-canonicaliser votre page par erreur ?
- □ Le Mobile-Friendly Test peut-il remplacer l'URL Inspection Tool pour auditer le crawl mobile ?
- □ Pourquoi Google ignore-t-il vos données structurées desktop après le mobile-first indexing ?
Once a site switches to mobile-first indexing, Google exclusively uses the structured data from the mobile version to generate all rich results—including those displayed on desktop. Before migration, each version (mobile and desktop) retains its own structured data for its context. Specifically, if your schema.org differs between mobile and desktop, only the mobile version will matter after the switch.
What you need to understand
What does Google mean by "mobile-first indexing" and how does it relate to structured data?<\/h3>
Mobile-first indexing means that Googlebot prioritizes crawling and indexing the mobile version of your site, even for desktop searches. This evolution, which started several years ago, is based on the observation that the majority of traffic now comes from smartphones.<\/p>
The direct consequence for structured data: once the migration is completed, Google will only read the schema.org markup present in your mobile version. Rich snippets, carousels, FAQ panels—everything relies on what Googlebot mobile detects. If your desktop version contains more complete or different schema.org data, it will be ignored.<\/p>
Before the switch to mobile-first indexing, Google applied a compartmentalized logic: the structured data from the desktop version were used to generate the rich results displayed on computers, while those from the mobile version were used for smartphones. Two indexes, two sources of markup.<\/p>
This approach theoretically allowed for content to be differentiated based on context, but also led to inconsistencies: a product could appear with one price in a rich snippet on mobile and another on desktop if the tags diverged. Since migration, this complexity has disappeared—at the cost of increased demands on the mobile version.<\/p>
Many sites have historically prioritized their desktop version for complete structured data: enriched articles with author, publication date, high-resolution images, detailed breadcrumbs. The mobile version, designed for lightweight presentation, sometimes carries a lighter or even incomplete markup.<\/p>
The result: after migrating to mobile-first indexing, these sites lose rich snippets on desktop without understanding why. Google no longer crawls the desktop version to extract the schema.org—and the Search Console does not always clearly signal this transition. This is a frequent blind spot in technical audits.<\/p>
How did Google behave before this migration?<\/h3>
Why does this unification pose problems for some sites?<\/h3>
SEO Expert opinion
Is this statement consistent with on-the-ground observations?<\/h3>
Yes, and it’s actually a recurring friction point in audits. We regularly observe sites migrated to mobile-first indexing that lose their rating stars, FAQ panels, or breadcrumbs in desktop SERPs—even though everything worked previously. The cause: a schema.org markup present only in the desktop version, or degraded on mobile for performance reasons.<\/p>
Google has been communicating about this topic for years, but the reality is that many technical teams still maintain distinct templates between mobile and desktop. And when responsive design is not total, structured data rarely follows suit. Poorly configured CMS exacerbate the problem: some schema.org modules only activate on desktop by default.<\/p>
Martin Splitt's statement is clear, but it leaves one technical point in the shade: what happens if the mobile version uses deferred JavaScript rendering to inject structured data? Does Googlebot mobile see them systematically? [To be verified]— in practice, we see that some sites with client-side JS hydration have their schema.org poorly indexed, especially if rendering takes more than 5 seconds.<\/p>
Another nuance: Google indicates it uses data from the mobile version "for all rich results," but does not clarify if content differences between mobile and desktop can affect eligibility. Example: a complete article on desktop, truncated on mobile with a "Read more" button. If the Article schema.org markup points to the truncated content, does Google consider the article incomplete? Yes, in some cases—and the loss of the rich snippet follows.<\/p>
Let’s be honest: there is no explicit exception in the statement. All sites migrated to mobile-first indexing follow this logic. But in practice, we observe atypical behaviors on highly authoritative domains or major news sites: Google sometimes seems to retain reading desktop structured data for certain types of content (events, job listings).<\/p>
These cases remain marginal and likely tied to accumulated trust signals rather than an exception to the rule. Don’t count on this for your site. Another situation where this rule loses relevance: sites that have never had a distinct desktop version—fully responsive from the start. In that case, the question doesn’t even arise.<\/p>
What nuances should we add to this rule?<\/h3>
In what cases does this rule not apply?<\/h3>
Practical impact and recommendations
What practical steps should be taken to align structured data?<\/h3>
First step: audit the parity between your mobile and desktop versions. Use Google’s rich results testing tool in mobile mode, then compare it with a desktop crawl of your strategic pages. Screaming Frog, Oncrawl, or a Python script with Beautiful Soup can extract and diff schema.org tags between the two versions.<\/p>
If you detect discrepancies, prioritize the mobile version: it is the authoritative version. Add or complete missing structured data—and if page weight or loading time constraints force you to lighten, choose the types of schema that are most impactful for your business (Product, Article, Recipe, Event depending on your sector).<\/p>
Don’t fall into the trap of blindly copying and pasting desktop structured data to mobile without adaptation. Some fields like "image" must point to URLs optimized for mobile (appropriate resolution, WebP format), otherwise Google may reject the markup or not display the rich snippet.<\/p>
Another common mistake: maintaining structured data in JSON-LD only in the of the desktop version, and forgetting it on mobile. If your CMS injects JSON-LD via a plugin or module, ensure that it activates properly on all versions. Microdata tags in the are less problematic, but are more cumbersome to maintain.<\/p>
Consult the Search Console, under "Settings" > "Crawling" to confirm that your site has indeed switched to mobile-first indexing. Then, navigate to "Enhancements" to see if Google correctly detects your structured data: products, recipes, FAQs, articles, events.<\/p>
Also test in real conditions: perform searches on your primary keywords from a desktop and check if the expected rich snippets appear. If you notice a disappearance, it's probably because the mobile version does not carry the appropriate markup. A quick test with the URL Inspection Tool in Googlebot mobile mode usually clears up any doubt.<\/p>
What mistakes should be avoided during this harmonization?<\/h3>
How can I check if my site is compliant after migration?<\/h3>
❓ Frequently Asked Questions
Mes structured data desktop disparaissent-elles complètement après la migration mobile-first ?
Comment savoir si mon site a basculé dans l'index mobile-first ?
Puis-je avoir des structured data différentes entre mobile et desktop sans pénalité ?
Les structured data injectées en JavaScript côté client sont-elles bien crawlées en mobile-first ?
Faut-il dupliquer toutes les structured data desktop sur mobile, même si ça alourdit la page ?
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