Http/2 setup help

I’m trying to get http/2 setup with ssl, but I keep getting the following error on the backend server.

2016-08-19 21:42:05.141 [INFO] [xxxx:41406] Status 400: Bad request method: PRI * HTTP/2.0

I followed the configuration on http://m12.io/blog/http-2-with-haproxy-and-nginx-guide