Guacamole protocol violation. Perhaps the version of guacamole-client is incompatible with this version of guacd?

I am having above error when connecting to gucamole .I am trying to connect using vnc protcol and flowing is my setup

`const GuacamoleLite = require('guacamole-lite');
 
const websocketOptions = {
    port: 8080 // we will accept connections to this port 
};
 
const guacdOptions = {
    port: 4822 // port of guacd 
};
 
const clientOptions = {
    crypt: {
        cypher: 'AES-256-CBC',
        key: 'MySuperSecretKeyForParamsToken12'
    }
};
 
const guacServer = new GuacamoleLite(websocketOptions, guacdOptions, clientOptions); `

and for web service

var express = require('express');
var app = express();
app.use('/', express.static(__dirname + '/public')); // ← adjust
var fs = require("fs");
var url = require('url');


app.get('/control', function (req, res) {
   var id = req.query.username;
   res.sendfile("guac_control.html");
})


app.get('/listUsers', function (req, res) {
   var id = req.query.username;

	/*{
    	"connection": {
        "type": "rdp",
        "settings": {
            "hostname": "10.0.0.12",
            "username": "Administrator",
            "password": "pAsSwOrD",
            "enable-drive": true,
            "create-drive-path": true,
            "security": "any",
            "ignore-cert": true,
            "enable-wallpaper": false
        }
    }
}
     config.setProtocol("vnc");
	        config.setParameter("hostname", UserIP);
	        config.setParameter("port", UserPort);
	        config.setParameter("password", "23213");
		 
	
	      //config.setParameter("reverse-connect", "true");
	       config.setParameter("password", "123123");
	        config.setParameter("color-depth", "32");
	       // config.setParameter("encodings", "zrle");
	        //nearly 5 mins
	        //config.setParameter("listen-timeout", "50000");
*/
   var clientConnection= {
    	connection : {
         type: "vnc",
         settings : {
             hostname: "127.0.0.1",
	     username :  "root",
             password : "root123"
        }
    }
}
    
   res.send(encrypt(clientConnection));
})

const crypto = require('crypto');

const clientOptions = {
    cypher: 'AES-256-CBC',
    key: 'MySuperSecretKeyForParamsToken12'
}

const encrypt = (value) => {
    const iv = crypto.randomBytes(16);
    const cipher = crypto.createCipheriv(clientOptions.cypher, clientOptions.key, iv);

    let crypted = cipher.update(JSON.stringify(value), 'utf8', 'base64');
    crypted += cipher.final('base64');

    const data = {
        iv: iv.toString('base64'),
        value: crypted
    };

    return new Buffer(JSON.stringify(data)).toString('base64');
};

var server = app.listen(8081, function () {

  var host = server.address().address
  var port = server.address().port

  console.log("web at http://%s:%s", host, port)

})`

And following are the logs

ay 25 14:47:00 ubuntu guacd[32881]: Protocol "vnc" selected May 25 14:47:00 ubuntu guacd[32881]: Guacamole protocol violation. Perhaps the version of guacamole-client is incompatible with this version of guacd? May 25 14:47:00 ubuntu guacd[32881]: Error reading "connect": Instruction read did not have expected opcode Please help me .

Thank You

[vadimpronin]

No reply, so I’m closing the issue. Feel free to reopen if needed

[vadimpronin]

Ok. One part of the problem was that guacamole-lite didn’t have any default connection parameters for VNC protocol (like height, width, dpi, port, etc). I’ve fixed that in 0.4.4 so please update and see if it works.

Another part is that you haven’t configured hostname and port in your connection settings. Instead you have dest-host and dest-port which are only used if you have vnc repeater.

These are the arguments that guacamole-lite is actually sending to your guacd (as per your log):

     "args" => "",
     "hostname" => "",
     "port" => "",
     "read-only" => "",
     "encodings" => "",
     "password" => "pAsSwOrD",
     "swap-red-blue" => "",
     "color-depth" => "",
     "cursor" => "",
     "autoretry" => "",
     "clipboard-encoding" => "",
     "dest-host" => "10.0.0.12",
     "dest-port" => "5901",
     "reverse-connect" => "",
     "listen-timeout" => "",
     "enable-sftp" => "",
     "sftp-hostname" => "",
     "sftp-port" => "",
     "sftp-username" => "",
     "sftp-password" => "",
     "sftp-private-key" => "",
     "sftp-passphrase" => "",
     "sftp-directory" => "",

As you see hostname and port are empty, but they mustn’t be.

Let me know if the update to 0.4.4 and fixing the parameters will work for you