Go 1.10.1 & 1.9.5 available. Go 1.8.X deprecated.

Change effective on 18 April 2018

Go version 1.10.1 is now the default and is used when either no version is specified or go1.10 is specified. Go version 1.9.5 is now used when go1.9 is specified. You can read more about the changes in these go versions here.

All Go 1.8.X versions are now deprecated, but still usable. We encourage everyone to upgrade to go1.10 at their earliest convenience.

See the Heroku Devcenter article for more information on how to specify the Go version for the dependency manager you are using.