Google changed how it handles soft 404 classifications and detection, and it was confirmed by John Mueller, a Google Search Relations Advocate. The search company now looks at each page by device type and potentially can assign the soft 404 classifications differently across the same URL on mobile versus desktop.
When a page returns, an HTTP status code of 200 is called soft 404, which means the page is okay and all is good. But in reality, the page cannot be found or does not really load content and should likely return a 404 status instead. When this happens, those pages will be flag by Google as soft 404s and treat the URL as a real 404 and not index the page.
Soft 404 classifications changed by Google and now look at a URL by device type. So if the company sees a URL and on desktop access the URL and then accesses it on mobile, it can potentially return a soft 404 for the desktop and not the mobile. The company detects the soft 404 status on a URL by URL basis and by device type. About a month ago, this changed happened.
SEOs are noticing one of two issues: In search console, SEOs see spikes in soft 404 errors but do not see an error in Google Search or queries in Google Search, no indexing pages. The page can return fine in Search Console Google for the mobile device type won’t show soft 404 errors. Based on the mobile crawl Google only shows soft 404s errors. The search console won’t show an error if the pages work fine on mobile. But to the desktop version, Google may assign soft 404 errors, so when Google is searched on desktop, pages indexed cannot be seen and coming up in Google Search. At the same time, the search consoles show everything is fine, but it is only okay on mobile, not on desktop.
“In Search Console, we do show soft 404s, but we show it for the mobile version. So if on the mobile version everything is okay on your side, then in Search Console, it will look like it’s indexed normally. But for desktop, you won’t be able to see that directly in Search Console,” said Mueller. The Google team is working on improving its soft 404 classifications.