bad RSV1, RSV2, or RSV3 bits

When I GET the address that call lua script with client example I receive error: "failed to receive the frame: bad RSV1, RSV2, or RSV3 bits"

nginx.conf:

server{
listen 80;
server_name comet.io;
location /cli{
default_type 'text/html';
content_by_lua_file 'path/to/lua/ws_client.lua';
}
}

ws_client.lua: <copy-paste from https://github.com/openresty/lua-resty-websocket#restywebsocketclient>

curl http://comet.io/cli
failed to receive the frame: bad RSV1, RSV2, or RSV3 bits

There is my ws server config:

server {
listen 8020;
    server_name comet.io;
    location /ser {
        proxy_pass http://comet.io:8010;
        proxy_http_version 1.1;
        proxy_set_header Upgrade "websocket";
        proxy_set_header Connection "Upgrade";
        proxy_set_header sec-websocket-key tfyt7uhy08yuh08909uoij;
        proxy_set_header sec-websocket-version 13;
    }
}

server {
    listen 8010;
    server_name comet.io;

    location /ser {
        default_type 'text/html';
        content_by_lua_file '/root/ws_server.lua';
    }
}

Start by reproducing the error with the shown curl request and reviewing nginx.conf, ws_client.lua, and ws_server.lua, including the referenced lua-resty-websocket client example. Trace the WebSocket handshake and frame exchange to determine which configuration or endpoint produces the invalid RSV bits; done means a confirmed cause and a reproducible correction or clear explanation.