diff --git a/src/DIRAC/Core/DISET/private/Transports/BaseTransport.py b/src/DIRAC/Core/DISET/private/Transports/BaseTransport.py
index 7001a703d63..d3fb1e618eb 100755
--- a/src/DIRAC/Core/DISET/private/Transports/BaseTransport.py
+++ b/src/DIRAC/Core/DISET/private/Transports/BaseTransport.py
@@ -42,7 +42,7 @@ class BaseTransport:
     def __init__(self, stServerAddress, bServerMode=False, **kwargs):
         self.bServerMode = bServerMode
         self.extraArgsDict = kwargs
-        self.byteStream = b""
+        self.byteStream = bytearray()
         self.packetSize = 1048576  # 1MiB
         self.stServerAddress = stServerAddress
         self.peerCredentials = {}
@@ -191,7 +191,7 @@ def receiveData(self, maxBufferSize=0, blockAfterKeepAlive=True, idleReceive=Fal
         maxBufferSize = max(maxBufferSize, 0)
         try:
             # Look either for message length of keep alive magic string
-            iSeparatorPosition = self.byteStream.find(b":", 0, 10)
+            iSeparatorPosition = self.byteStream.find(b":")
             keepAliveMagicLen = len(BaseTransport.keepAliveMagic)
             isKeepAlive = self.byteStream.find(BaseTransport.keepAliveMagic, 0, keepAliveMagicLen) == 0
             # While not found the message length or the ka, keep receiving
@@ -204,9 +204,10 @@ def receiveData(self, maxBufferSize=0, blockAfterKeepAlive=True, idleReceive=Fal
                 if not retVal["Value"]:
                     return S_ERROR("Peer closed connection")
                 # New data!
-                self.byteStream += retVal["Value"]
-                # Look again for either message length of ka magic string
-                iSeparatorPosition = self.byteStream.find(b":", 0, 10)
+                self.byteStream.extend(retVal["Value"])
+
+                # Look again for either message length or keep alive magic string
+                iSeparatorPosition = self.byteStream.find(b":")
                 isKeepAlive = self.byteStream.find(BaseTransport.keepAliveMagic, 0, keepAliveMagicLen) == 0
                 # Over the limit?
                 if maxBufferSize and len(self.byteStream) > maxBufferSize and iSeparatorPosition == -1:
@@ -214,7 +215,7 @@ def receiveData(self, maxBufferSize=0, blockAfterKeepAlive=True, idleReceive=Fal
             # Keep alive magic!
             if isKeepAlive:
                 gLogger.debug("Received keep alive header")
-                # Remove the ka magic from the buffer and process the keep alive
+                # Remove the keep-alive magic from the buffer and process the keep-alive
                 self.byteStream = self.byteStream[keepAliveMagicLen:]
                 return self.__processKeepAlive(maxBufferSize, blockAfterKeepAlive)
             # From here it must be a real message!
@@ -225,7 +226,7 @@ def receiveData(self, maxBufferSize=0, blockAfterKeepAlive=True, idleReceive=Fal
             if readSize >= pkgSize:
                 # If we already have all the data we need
                 data = pkgData[:pkgSize]
-                self.byteStream = pkgData[pkgSize:]
+                self.byteStream = self.byteStream[pkgSize + iSeparatorPosition + 1 :]
             else:
                 # If we still need to read stuff
                 pkgMem = BytesIO()
@@ -245,11 +246,12 @@ def receiveData(self, maxBufferSize=0, blockAfterKeepAlive=True, idleReceive=Fal
                 # Data is here! take it out from the bytestream, dencode and return
                 if readSize == pkgSize:
                     data = pkgMem.getvalue()
-                    self.byteStream = b""
-                else:  # readSize > pkgSize:
+                    self.byteStream = bytearray()  # Reset the byteStream
+                else:
                     pkgMem.seek(0, 0)
                     data = pkgMem.read(pkgSize)
-                    self.byteStream = pkgMem.read()
+                    self.byteStream = bytearray(pkgMem.read())  # store the rest in bytearray
+
             try:
                 data = MixedEncode.decode(data)[0]
             except Exception as e:
diff --git a/src/DIRAC/Core/Utilities/DEncode.py b/src/DIRAC/Core/Utilities/DEncode.py
index 3a20b868192..bae1a2179c1 100755
--- a/src/DIRAC/Core/Utilities/DEncode.py
+++ b/src/DIRAC/Core/Utilities/DEncode.py
@@ -521,7 +521,7 @@ def decode(data):
     if not data:
         return data
     # print("DECODE FUNCTION : %s" % g_dDecodeFunctions[ sStream [ iIndex ] ])
-    if not isinstance(data, bytes):
+    if not isinstance(data, (bytes, bytearray)):
         raise NotImplementedError("This should never happen")
     return g_dDecodeFunctions[data[0]](data, 0)