It means x/net/html package is missing from the Go’s import path. I am going to paraphrase from “The Go Programming” book that says, The golang.org/x/… repositories hold packages designed and maintained by Go team for applications such as networking, internationalized text processing, mobile platforms, image manipulation, cryptography, and developer tools. These packages are not in the standard library because they’re still under development or because they’re rarely needed by the majority of Go Programmers.