Why is a map page reported as a "soft 404" in Google Search Console?

Question

I'm trying to debug Soft 404 errors in Search Console. The Soft 404's keep appearing. If I try to "Fetch as Google" it seems like they returns a valid response.

HTTP/1.1 200 OK
Server: TornadoServer/4.2.1
Content-Type: text/html; charset=UTF-8
Strict-Transport-Security: max-age=31536000
Date: Mon, 14 Mar 2016 14:13:18 GMT

The page is a regular page in a Tornado application showing a full screen with google maps and a navigation header. Google explanation of Soft 404 is:

[...] server returns a code other than 404 or 410 for a non-existent page (or redirecting users to another page, such as the homepage, instead of returning a 404). This creates a poor experience for searchers and search engines.

This page is, however, existing... (and fetches correctly through Search Console). What can cause these Soft 404s?

Answer 1

Soft 404s are caused when Google thinks you should have returned a 404/410 for a request, but instead returned 200. Google defines this as when ‘the content of the page is entirely unrelated to the HTTP response returned by the server’.

As such, you need the content of the page to be sufficient for the page to be recognised as such rather than being inferred as an error. The content of the page is what causes a soft 404, not the page headers.

Make sure the page has a relevant title and possibly add some content within a noscript tag. You can also try adding structured data to the page to help search engines understand the content.