Google announced last month that they would be using a brand new mobile / smartphone user-agent for crawling starting on April 18, 2016.  Google has now confirmed this is live.

For most users, the change won’t be noticeable.  But if you have noticed a recent decline in the mobile UA crawling your site, or you have suddenly lost your mobile friendly tag and ranking boost, you may be blocking the new user-agent.  Google pre-announced the change for those who were allowing Googlebot by name only, as the name change could result in some sites blocking the new mobile Googlebot’s useragent.

Here is the new user-agent:

Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5X Build/MMB29P) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.96 Mobile Safari/537.36 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)

This Googlebot is still crawling from the same IPs as the old one, according to Google.

But it is worth doing a quick health check, especially if you use any kind of “bad bot” blocking tools or software, to ensure the mobile Googlebot is able to crawl as intended.  You can also use Google’s mobile friendly tester to double check.