Error when running Example Network Discovery

[MrPure3D]

Hi,

Im getting this error on Server when Client is Searching for a Server, this on Both Apple M1 and Windows. port on NetworkManager: 7770 and local IP Port on ExampleNetworkDiscovery: 47777

Any ideas?

Invalid allocation label passed to UnsafeUtility::Free UnityEngine.StackTraceUtility:ExtractStackTrace () Unity.Netcode.FastBufferWriter:Dispose () (at Library/PackageCache/com.unity.netcode.gameobjects@1.2.0/Runtime/Serialization/FastBufferWriter.cs:125) NetworkDiscovery`2/d__27<DiscoveryBroadcastData, DiscoveryResponseData>:MoveNext () (at Library/PackageCache/com.community.netcode.extensions@e9f53f86a0/Runtime/NetworkDiscovery/NetworkDiscovery.cs:224) UnityEngine.UnitySynchronizationContext:ExecuteTasks ()

[unnanego]

Same here

[paatz04]

same here

[Kinggrass]

Unfortunatly the same :(

[Kinggrass]

Don't know what explicitly is wrong, but I explicitly disposed the FastBufferWriter and now it don't appear anymore. By changing from following in NetworkDiscovery.cs:

to:

[Kinggrass]

Maybe the underlying handle is not valid anymore after the async task is returning. Maybe the author could better explain what could happen here.

[yannoid]

Same here.

Removing the error with @Kinggrass 's solution won't work for me since it doesn't connect the client after that.

[jpvanoosten]

The issue occurs because the FastBufferWriter uses Allocator.Temp for the memory allocation which very likely results in the memory handle becoming invalid at the end of the current frame (the backing memory for the FastBufferWriter is disposed before the FastBufferWriter using that memory is disposed). Since this is an async method, there is no guarantee the function will complete within 1 frame. If the SendAsync function doesn't return immediately, then the error will occur.

To fix this, change Allocator.Temp to Allocator.Persistent when creating a FastBufferReader or FastBufferWriter inside of an async function. For example, this is what ReceiveBroadcastAsync should look like:

    async Task ReceiveBroadcastAsync()
    {
        UdpReceiveResult udpReceiveResult = await m_Client.ReceiveAsync();

        var segment = new ArraySegment<byte>(udpReceiveResult.Buffer, 0, udpReceiveResult.Buffer.Length);
        using var reader = new FastBufferReader(segment, Allocator.Persistent);

        try
        {
            if (ReadAndCheckHeader(reader, MessageType.BroadCast) == false)
            {
                return;
            }

            reader.ReadNetworkSerializable(out TBroadCast receivedBroadcast);

            if (ProcessBroadcast(udpReceiveResult.RemoteEndPoint, receivedBroadcast, out TResponse response))
            {
                using var writer = new FastBufferWriter(1024, Allocator.Persistent, 1024 * 64);
                WriteHeader(writer, MessageType.Response);

                writer.WriteNetworkSerializable(response);
                var data = writer.ToArray();

                await m_Client.SendAsync(data, data.Length, udpReceiveResult.RemoteEndPoint);
            }
        }
        catch (Exception e)
        {
            Debug.LogException(e);
        }
    }

The ReceiveResponseAsync method should also be updated accordingly.

[MattGrayUL]

The solution from @jpvanoosten fixed the issue for me