Due to reasons of domestic network, access https://golang.org/ site will be limited. So go get the time to download other third-party packages, if the third-party packages and quoted under the package https://golang.org/x/, usually the download fails, it will report this error.
VPN solution is usually allocated to overseas download, download here I put a good package put on github. Facilitate use.
Download: https: //github.com/2wangjingjun8/golang.org