Error during WebSocket handshake: Unexpected response code: 400

nginx-for-websoket-failure.conf

location / {
  proxy_pass http://localhost:8080;
  proxy_http_version 1.1;
  proxy_set_header Upgrade $http_upgrade;
  proxy_set_header Connection "upgrade";
  proxy_set_header Host $host;
}

# Usually it only needs to add these lines, as we probably have other ones been set
#
# proxy_http_version 1.1;
# proxy_set_header Upgrade $http_upgrade;
# proxy_set_header Connection "upgrade";