"Temporarily unreachable" when using fetch as Googlebot from Webmasters Tools

According to Google, it's because:

  1. Fetch as Google can't currently fetch your URL because the server took too long to reply.
  2. Or Fetch as Google cancelled your fetch because too many consecutive requests were made to the server for different URLs.

I've witnessed this happening a few times in the past. More often than not, it's an intermittent problem that goes away after a short period of time.

Important note:

Note the URL is not unreachable for all of Google - It is just unreachable for the Fetch as Google simulation tool.

Old thread but I had this issue, it was due to making changes on cloudflare supported TLS version. Google does not support tls 1.3 yet - make sure your servers allows tls 1.2