Notes from the Google Webmaster Hangout on the 24th of February, 2017.
Crawling Might be Blocked on a Blacklisted IP, Network Configuration or Bot Protection
Google doesn’t block the crawling of a specific domain, but you could be on an IP which has been blacklisted or have a network issue. Check if other sites hosted on the same server are having similar problems. Sometimes a bot protection on a server can cause issues.
Pages Can Be Assigned Multiple Hreflang Tags
Pages can have multiple hreflang tags going to the same page for different countries.
Markup Doesn't Make the Sitelinks Search Box Appear
If Google doesn’t show a searchlink search box, the markup won’t make it appear. It just allows searches to take place on the site instead of Google.
Hreflang Pages Can Be Canonicalised to One Version
If you hreflang a set of pages, and canonicalise to one version, Google may show the different URLs but all with the title and description of the canonical version. However John advises against this configuration.
Server Security Plugins Can Cause Unauthorised Errors
If Google Search Console is reporting a large number of unauthorised errors, it might be caused by a server configuration which is blocking Googlebot.
Add AMP Links to Mobile Pages for Mobile-first
You should add AMP links to your mobile pages.
Google Sometimes Makes Requsts with If-modified-since Headers
Googlebot sometimes makes requests using an If-modified-since request, in which case a 304 response is fine provided the content hasn’t changed since the date specified in the If-modified-since header.
Videos Hosted on Google Drive 'should' be Indexable
John thinks that Google will index videos hosted on Google drive and show a video snippet for the page which links to it.
Fetch and Render Will Show Rendered HTML in the Future
Don't Mix Different Structured Data Markup for the Same Items
You can use any of the supported markup types, but you shouldn’t mix types for a single item.