@netvipe 1.10 is the latest release. Does your issue reproduce on that version as well? can you provide a snippet of code that reproduces your issue?

The following program runs without issue for me on macOS using 1.10 (I see you’re running windows so maybe that’s a factor):

package main

import (
        "log"

        "golang.org/x/crypto/chacha20poly1305"
)

func main() {
        c, err := chacha20poly1305.New(make([]byte, chacha20poly1305.KeySize))
        if err != nil {
                log.Fatal(err)
        }
        log.Printf("cipher: %+v", c)
}

@andybons My various test snippets look very similar to yours. The only thing missing is a call for "c.Open(...)". But a simple import and a reference is enough for the error message to appear.

The corresponding lines in chacha20poly1305_amd64.{s,go} are identical, so I don't think the new go version will fix it.

The error message only appears on the stated Windows system. It does not appear on another Linux dev system.

Reason for the issue seems to be the Intel i5-3570K CPU, which does not support AVX2 at all.
The Linux server does.

I'm pretty sure it's the following code section in chacha20poly1305_amd64.go:

@Line 61:
	_, ebx7, _, _ := cpuid(7, 0)
	haveAVX2 := isSet(5, ebx7) && haveAVX
	haveBMI2 := isSet(8, ebx7)

I already though about bypassing it, which is pretty simple, but I don't like to modify public sources for my local build system only. There must be a smarter way ;-)

/cc @FiloSottile @rogpeppe

Are you using latest version of x/crypto?
https://go-review.googlesource.com/c/crypto/+/41862 removed dependency on runtime.cpuid_*
And go1.9 removed cpuid_* from runtime. So this looks like a problem with stale x/crypto

You are right. A complete clear of automatically downloaded sources and cached build files in src and pkg removed the issue. I've already upgraded to go 1.9.4 before creating the ticket. But that did not clear the caches etc. My fault.
Many thanks for the support!