diff --git a/TLSharp.Core/Auth/Step3_CompleteDHExchange.cs b/TLSharp.Core/Auth/Step3_CompleteDHExchange.cs
index 8ba8f5a..b881e40 100644
--- a/TLSharp.Core/Auth/Step3_CompleteDHExchange.cs
+++ b/TLSharp.Core/Auth/Step3_CompleteDHExchange.cs
@@ -175,7 +175,7 @@ namespace TLSharp.Core.Auth
 
                         if (!newNonceHash1.SequenceEqual(newNonceHashCalculated))
                         {
-                            throw new InvalidOperationException("invalid new nonce hash");
+                            throw new InvalidNewNonceHashException();
                         }
 
                         //logger.info("generated new auth key: {0}", gab);
@@ -206,4 +206,11 @@ namespace TLSharp.Core.Auth
             }
         }
     }
+    internal class InvalidNewNonceHashException : Exception
+    {
+        internal InvalidNewNonceHashException() : base($"invalid new nonce hash")
+        {
+
+        }
+    }
 }
diff --git a/TLSharp.Core/Network/MtProtoSender.cs b/TLSharp.Core/Network/MtProtoSender.cs
index 8a959ca..5dcb483 100644
--- a/TLSharp.Core/Network/MtProtoSender.cs
+++ b/TLSharp.Core/Network/MtProtoSender.cs
@@ -110,7 +110,7 @@ namespace TLSharp.Core.Network
             using (var inputReader = new BinaryReader(inputStream))
             {
                 if (inputReader.BaseStream.Length < 8)
-                    throw new InvalidOperationException($"Can't decode packet");
+                    throw new DecodePacketException();
 
                 ulong remoteAuthKeyId = inputReader.ReadUInt64(); // TODO: check auth key id
                 byte[] msgKey = inputReader.ReadBytes(16); // TODO: check msg_key correctness
@@ -313,6 +313,15 @@ namespace TLSharp.Core.Network
                 {
                     throw new CloudPasswordNeededException("This Account has Cloud Password !");
                 }
+                else if (errorMessage == "AUTH_KEY_UNREGISTERED")
+                {
+                    //
+                    throw new AuthKeyUnregisteredException();
+                }
+                else if (errorMessage == "RPC_MCGET_FAIL")
+                {
+                    throw new RpcMcGetFailException();
+                }
                 else
                 {
                     throw new InvalidOperationException(errorMessage);
@@ -378,7 +387,7 @@ namespace TLSharp.Core.Network
                 case 20:
                     throw new InvalidOperationException("message too old, and it cannot be verified whether the server has received a message with this msg_id or not");
                 case 32:
-                    throw new InvalidOperationException("msg_seqno too low (the server has already received a message with a lower msg_id but with either a higher or an equal and odd seqno)");
+                    throw new MsgSeqnoTooLowException();
                 case 33:
                     throw new InvalidOperationException(" msg_seqno too high (similarly, there is a message with a higher msg_id but with either a lower or an equal and odd seqno)");
                 case 34:
@@ -535,6 +544,37 @@ namespace TLSharp.Core.Network
         }
     }
 
+    internal class DecodePacketException : Exception
+    {
+        internal DecodePacketException() : base($"Can't decode packet.")
+        {
+
+        }
+    }
+    public class AuthKeyUnregisteredException : Exception
+    {
+        internal AuthKeyUnregisteredException() : base($"Auth key is unregistered.")
+        {
+
+        }
+    }
+
+    internal class RpcMcGetFailException : Exception
+    {
+        internal RpcMcGetFailException() : base($"Rpc Mc Get Fail.")
+        {
+
+        }
+    }
+
+    internal class MsgSeqnoTooLowException : Exception
+    {
+        internal MsgSeqnoTooLowException() : base($"msg_seqno too low (the server has already received a message with a lower msg_id but with either a higher or an equal and odd seqno)")
+        {
+
+        }
+    }
+    
     internal abstract class DataCenterMigrationException : Exception
     {
         internal int DC { get; private set; }
diff --git a/TLSharp.Core/Network/TcpTransport.cs b/TLSharp.Core/Network/TcpTransport.cs
index 31bd6b4..2ca6c99 100644
--- a/TLSharp.Core/Network/TcpTransport.cs
+++ b/TLSharp.Core/Network/TcpTransport.cs
@@ -28,7 +28,7 @@ namespace TLSharp.Core.Network
         public async Task Send(byte[] packet)
         {
             if (!_tcpClient.Connected)
-                throw new InvalidOperationException("Client not connected to server.");
+                throw new TcpClientNotConnectedException();
 
             var tcpMessage = new TcpMessage(sendCounter, packet);
 
@@ -42,7 +42,7 @@ namespace TLSharp.Core.Network
 
             var packetLengthBytes = new byte[4];
             if (await stream.ReadAsync(packetLengthBytes, 0, 4) != 4)
-                throw new InvalidOperationException("Couldn't read the packet length");
+                throw new TcpClientCouldntReadPacketLengthException();
             int packetLength = BitConverter.ToInt32(packetLengthBytes, 0);
 
             var seqBytes = new byte[4];
@@ -101,4 +101,20 @@ namespace TLSharp.Core.Network
                 _tcpClient.Close();
         }
     }
+    internal class TcpClientNotConnectedException : Exception
+    {
+        internal TcpClientNotConnectedException() : base($"Client not connected to server.")
+        {
+
+        }
+    }
+    internal class TcpClientCouldntReadPacketLengthException : Exception
+    {
+        internal TcpClientCouldntReadPacketLengthException() : base($"Couldn't read the packet length")
+        {
+
+        }
+    }
+
+    
 }