A first chance exception

I was studying sockets in C#, and after I managed coding a basic two-person chat, I decided to move on to multiplayer chat, which has a server and X clients.

Now, there is a problem popping up even when there is only one client connected. As soon as the client connects, both the server and client get a message, "Another client connected" or "Connected to server". The second they both clicked OK, the client's program crashes, follows by the server one (I will deal with disconnecting later, I want to get it working first). And as you can guess from the title, the only thing I get is "A first chance exception" which even after googling or reading here, I couldn't stop it from coming, nor understanding WHY it was coming.

Here are the two lines from the debugger output:

A first chance exception of type 'System.FormatException' occurred in mscorlib.dll

The program '[6808] Chat - sockets.vshost.exe: Managed (v4.0.30319)' has exited with code 0 (0x0).

Try-catch didn't work when trying to catch this exception. And as I said before, the program crashes even on debugging mode, showing no error.

And here is the code:

Client connect callback:

private void ClientConnectCallback(IAsyncResult res)
{
    serverSocket.EndConnect(res);
    MessageBox.Show("Server connected.");
    serverSocket.BeginReceive(buffer, 0, buffer.Length, SocketFlags.None, new AsyncCallback(ClientRecieveCallback), null);
}

buffer is a local variable, a byte array sized as 1000. serverSocket is a socket on which we use the 'BeginConnect' method.

And this is the server accept client callback:

private void ServerAcceptCallback(IAsyncResult res)
{
    //Recieving the socket.
    Socket tempSocket = localHost.EndAccept(res);

    //Creating a new buffer for it.
    byte[] tempBuffer = new byte[1000];

    //Adding the socket to the array.
    Socket[] tempArray = clients;
    clients = new Socket[tempArray.Length + 1];
    Array.Copy(tempArray, clients, tempArray.Length);
    clients[clients.Length - 1] = tempSocket;

    //Adding the buffer to the list.
    buffers.Add(tempBuffer);
    MessageBox.Show("Another client connected");

    //Begin receive data.
    tempSocket.BeginReceive(tempBuffer, 0, tempBuffer.Length, SocketFlags.None, new AsyncCallback(ServerRecieveCallback), null);
    localHost.BeginAccept(new AsyncCallback(ServerAcceptCallback), null);
    numOfPpl++;
    ServerSend("~~~NumOfPpl:" + numOfPpl);
}

localHost is a socket which we bind to the port, and to ANY address, and then we call it to 'Listen(0)'. tempBuffer is a new byte array which we create for using as a buffer for this connection only. clients is a socket array, containing the clients of the server. buffers is a List of the buffers of the clients.

numOfPpl is the number of people in the current conversation, and by calling ServerSend with the text "~~~NumOfPpl:", the clients receive the next number as the number of people and not a message, and change it respectively in their computer.

I hope I made myself clear, my first question in this site.

Actually, even a piece of information that will help me to get myself further (because I am left with nothing to try now) will help a lot.