Google has identified the two most frequent problems when assessing sites for mobile-first indexing.
As previously mentioned by Google, sites are only transitioned to mobile-first indexing when they are deemed ready.
To date, over half of the pages displayed in global search results have been transitioned to mobile-first indexing.
Site owners will be notified when this transition occurs through a notification sent via Search Console.
If your site has not been moved to mobile-first indexing, it may be because Google has not yet evaluated it.
Alternatively, if your site is not using responsive web design, there may be two issues hindering the transition.
### Structured data on mobile pages is missing
When structured data is used on the desktop version of a page, it should also be present on the mobile version.
“This is important because with mobile-first indexing, we’ll only use the mobile version of your page for indexing, and will otherwise miss the structured data.”
Google suggests testing each version of the page for structured data and comparing the results.
For the mobile version, Google recommends checking the source code while simulating a mobile device using Chrome DevTools.
You can also check the HTML generated with the mobile-friendly testing tool.
### Alt-text is missing on mobile pages
Similarly, if alt-text is used for images on desktop pages, it must also be used on mobile pages.
Alt-text helps Google better understand the context of images on web pages.
Google recommends checking “img” tags in the source code of the mobile version.
Search the source code for “img” tags and ensure mobile pages are providing appropriate alt-attributes.
### How to check for mobile-first indexing manually
If you still haven’t received the mobile-first indexing notification, there is a method to check manually.
Use Google’s URL inspection tool, which allows site owners to verify how a URL was last crawled and indexed.
Run a URL through the tool—usually, just the homepage is sufficient—and check for “Googlebot smartphone” as shown above.
