diff --git a/openpype/hosts/harmony/api/TB_sceneOpened.js b/openpype/hosts/harmony/api/TB_sceneOpened.js
index 610b0a73bb..e7cd555332 100644
--- a/openpype/hosts/harmony/api/TB_sceneOpened.js
+++ b/openpype/hosts/harmony/api/TB_sceneOpened.js
@@ -35,7 +35,11 @@ function Client() {
     self.pack = function(num) {
         var ascii='';
         for (var i = 3; i >= 0; i--) {
-            ascii += String.fromCharCode((num >> (8 * i)) & 255);
+          var hex = ((num >> (8 * i)) & 255).toString(16);
+          if (hex.length < 2){
+            ascii += "0";
+          }
+          ascii += hex;
         }
         return ascii;
     };
@@ -279,12 +283,21 @@ function Client() {
     };
 
     self._send = function(message) {
-      var codec_name = new QByteArray().append("ISO-8859-1");
+      /** Harmony 21.1 doesn't have QDataStream anymore.
+
+      This means we aren't able to write bytes into QByteArray so we had
+      modify how content lenght is sent do the server.
+      Content lenght is sent as string of 8 char convertible into integer
+      (instead of 0x00000001[4 bytes] > "000000001"[8 bytes]) */
+      var codec_name = new QByteArray().append("UTF-8");
+
       var codec = QTextCodec.codecForName(codec_name);
       var msg = codec.fromUnicode(message);
       var l = msg.size();
-      var coded = new QByteArray().append('AH').append(self.pack(l)).append(msg);
-      self.socket.write(new QByteArray(coded));
+      var header = new QByteArray().append('AH').append(self.pack(l));
+      var coded = msg.prepend(header);
+
+      self.socket.write(coded);
       self.logDebug('Sent.');
     };
 
diff --git a/openpype/hosts/harmony/api/server.py b/openpype/hosts/harmony/api/server.py
index 88cfe54521..0de359ec61 100644
--- a/openpype/hosts/harmony/api/server.py
+++ b/openpype/hosts/harmony/api/server.py
@@ -88,21 +88,25 @@ class Server(threading.Thread):
         """
         current_time = time.time()
         while True:
-
+            self.log.info("wait ttt")
             # Receive the data in small chunks and retransmit it
             request = None
-            header = self.connection.recv(6)
+            header = self.connection.recv(10)
             if len(header) == 0:
                 # null data received, socket is closing.
                 self.log.info(f"[{self.timestamp()}] Connection closing.")
                 break
+
             if header[0:2] != b"AH":
                 self.log.error("INVALID HEADER")
-            length = struct.unpack(">I", header[2:])[0]
+            content_length_str = header[2:].decode()
+
+            length = int(content_length_str, 16)
             data = self.connection.recv(length)
             while (len(data) < length):
                 # we didn't received everything in first try, lets wait for
                 # all data.
+                self.log.info("loop")
                 time.sleep(0.1)
                 if self.connection is None:
                     self.log.error(f"[{self.timestamp()}] "
@@ -113,7 +117,7 @@ class Server(threading.Thread):
                     break
 
                 data += self.connection.recv(length - len(data))
-
+            self.log.debug("data:: {} {}".format(data, type(data)))
             self.received += data.decode("utf-8")
             pretty = self._pretty(self.received)
             self.log.debug(