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Bug "Received error message from Relay: allocation ID client mismatch."

Discussion in 'Multiplayer' started by Del_Chenzo, Jan 11, 2023.

  1. Del_Chenzo

    Del_Chenzo

    Joined:
    Jun 27, 2020
    Posts:
    6
    The error, "Received error message from Relay: allocation ID client mismatch.", appeared with no reference to the script it came from and without further explanation. It appears after I've started a host and the player prefab is instantiated with a somewhat random time after everything is set up. Although I found through Relay's Documentation what this means, I still have no idea how to fix it. Here is the definition: " ErrClientPlayerMismatch is returned when a client has sent a RELAY message to the server using an unknown network connection. It is intended to inform the client that the IP address they are using has changed from the one the Relay server is aware of. This error message indicates the client should re-bind with a new BIND message". I've been grappling with this issue for hours now and still cannot find the source of this issue. I am running Unity version 2021.3.15f1.
     
  2. simon-lemay-unity

    simon-lemay-unity

    Unity Technologies

    Joined:
    Jul 19, 2021
    Posts:
    278
    I'm assuming you're using Netcode for GameObjects? And just so I understand the timeline of events correctly, this is what happens?
    1. Start a host (using NetworkManager.StartHost).
    2. Instantiate the player prefab.
    3. Some random amount of time (approximately how long? are we talking minutes or seconds?).
    4. The error message appears.
     
  3. Del_Chenzo

    Del_Chenzo

    Joined:
    Jun 27, 2020
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    Yes I am using Netcode for GameObjects. You have the order correct and on the third step it takes a few seconds for the error message to pop up. I have also had other people run the game on their computers with the same error popping up.
     
  4. simon-lemay-unity

    simon-lemay-unity

    Unity Technologies

    Joined:
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    Posts:
    278
    To give you some context as to what causes this error, this happens if the allocation is alive and the Relay server receives a message (could just be a simple heartbeat) while the connection handshake with the server has not been performed or has not been completed yet. The Relay server will then answer this unexpected message with an error, which is what is logged here (there's no stack trace because it's logged from Burst-compiled code).

    But that's kind of unexpected that you're observing this here. Normally the transport would prevent any messages from being sent until the handshake completes. The only scenario I've seen it happen is if your IP address would have changed (which renders the previous handshake invalid), but that doesn't appear to be the case here.

    Some extra information that could help us debug your issue:
    1. What version of Netcode for GameObjects are you using?
    2. What protocol are you using to communicate with the Relay server? You can find that out in the code that grabs the allocation from the Relay SDK. At some point there should be either the "dtls" string or the "udp" string.
    3. Do network communications still work after the error appears or does everything "freeze"? That is, are network variables and transforms still synchronized once the error shows up?
    4. If you set the 'Heartbeat Timeout Ms' setting under the 'Unity Transport' component to 0, does it still occur?
     
  5. Del_Chenzo

    Del_Chenzo

    Joined:
    Jun 27, 2020
    Posts:
    6
    1. Version 1.1.0
    2. If you're talking about the 'Protocol Type' field in the Unity Transport Component, then it is set to Relay Unity Transport. Or are you talking about this? Screenshot 2023-01-11 173705.png
    3. Network communications continue but are slowed significantly and things like network client transforms are updated infrequently in comparison to when I did not receive this error.
    4. The error continues to occur after changing 'Heartbeat Timeout Ms' to 0. I should also mention the error is printed more frequently to the console when changing this value to 0.
     
    Last edited: Jan 11, 2023
  6. simon-lemay-unity

    simon-lemay-unity

    Unity Technologies

    Joined:
    Jul 19, 2021
    Posts:
    278
    Could you try updating to version 1.2.0? It may not show up in the package manager, but you can install it manually by name or by modifying the manifest directly.

    By protocol type I meant the protocol used to create the
    RelayServerData
    object. If you look at this page of the documentation, you can see that at the end of the code sample it creates the
    RelayServerData
    object using the "dtls" connection type. If that's the connection type you are using, could you try changing it to "udp"?

    If you are comfortable using that tool, you could try capturing the network traffic using Wireshark. If you could share a capture of the traffic during a reproduction of the issue, that would be useful in figuring out what is going on here. Do make sure you're using the "udp" connection type if you try that though, otherwise everything will be encrypted and we won't see much.
     
  7. Del_Chenzo

    Del_Chenzo

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    Jun 27, 2020
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    I see I never seem to have explicitly stated which protocol I was using in my code. In place of RelayServerData I have a struct called RelayHostData which has all the information from the allocation that is created but I don't have a field for the connection type. Here is a snippet of the code that creates the server allocation and feeds the transport the relay data:
    Code (CSharp):
    1. public async Task<RelayHostData> SetupRelay(){
    2.         InitializationOptions options = new InitializationOptions()
    3.         .SetEnvironmentName(environment);
    4.  
    5.         await UnityServices.InitializeAsync(options);
    6.  
    7.         if(!AuthenticationService.Instance.IsSignedIn){
    8.             await AuthenticationService.Instance.SignInAnonymouslyAsync();
    9.         }
    10.  
    11.        
    12.         Allocation allocation = await Relay.Instance.CreateAllocationAsync(maxConnections);
    13.  
    14.         RelayHostData relayHostData = new RelayHostData
    15.         {
    16.             key = allocation.Key,
    17.             Port = (ushort)allocation.RelayServer.Port,
    18.             AllocationID = allocation.AllocationId,
    19.             AllocationIDBytes = allocation.AllocationIdBytes,
    20.             IPv4Address = allocation.RelayServer.IpV4,
    21.             ConnectionData = allocation.ConnectionData
    22.            
    23.         };
    24.        
    25.         relayHostData.JoinCode = await Relay.Instance.GetJoinCodeAsync(relayHostData.AllocationID);
    26.  
    27.         Transport.SetRelayServerData(relayHostData.IPv4Address, relayHostData.Port, relayHostData.AllocationIDBytes, relayHostData.key, relayHostData.ConnectionData);
    28.  
    29.         Debug.Log($"Join code created: {relayHostData.JoinCode}");
    30.         joinText.text = relayHostData.JoinCode;
    31.        
    32.  
    33.         return relayHostData;
    34.     }
    Here is the RelayHostData struct as well:
    Code (CSharp):
    1. public struct RelayHostData{
    2.     public string JoinCode;
    3.     public string IPv4Address;
    4.     public ushort Port;
    5.     public Guid AllocationID;
    6.     public byte[] AllocationIDBytes;
    7.     public byte[] ConnectionData;
    8.     public byte[] key;
    9. }
     
  8. simon-lemay-unity

    simon-lemay-unity

    Unity Technologies

    Joined:
    Jul 19, 2021
    Posts:
    278
    Directly using the `RelayServer` object from the allocation will lead to the "udp" connection type to be used. It's basically an artefact of when this was the only connection type supported. It's recommended to use the new `RelayServerData` mechanism, but it's not strictly necessary.
     
  9. Del_Chenzo

    Del_Chenzo

    Joined:
    Jun 27, 2020
    Posts:
    6
    Interesting...
    I refactored my code to be more up to date with the documentation and have not seen the error appear. Most notably, I've changed the use of the "Relay" class to the "RelayService" class, got rid of my "RelayHostData" and "RelayJoinData" structs (I don't know why I made them, they were quite redundant) and replaced them with the "RelayServerData" struct instead, and I also set the connection type to "dtls" in the "RelayServerData" constructor. Despite these changes, I still don't know why this is too different from my previous code. Is there a difference between the "RelayService" and "Relay" classes? They both have the same functions needed to create and join allocations. Or was it because I switched the connection type to "dtls" instead of the default "udp"? Edit: I tried changing to the "udp" connection type and was not met with any errors.
     
  10. simon-lemay-unity

    simon-lemay-unity

    Unity Technologies

    Joined:
    Jul 19, 2021
    Posts:
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    That's quite weird. I wouldn't expect these changes to make the error disappear (although I'm not familiar enough with the differences between
    Relay
    and
    RelayService
    to make any worthwhile judgment about that specifically). But I'm not going to argue with good news. Glad to read that you got it working!
     
  11. Del_Chenzo

    Del_Chenzo

    Joined:
    Jun 27, 2020
    Posts:
    6
    Thanks for helping me on this issue. I was really pulling my hair out on this one, and thanks to you I better understand how netcode and relay work :).