diff --git a/Assets/Mirror/Transports/KCP/KcpTransport.cs b/Assets/Mirror/Transports/KCP/KcpTransport.cs
index b0503ee45..af489b407 100644
--- a/Assets/Mirror/Transports/KCP/KcpTransport.cs
+++ b/Assets/Mirror/Transports/KCP/KcpTransport.cs
@@ -116,7 +116,7 @@ protected virtual void Awake()
             client = new KcpClient(
                 () => OnClientConnected.Invoke(),
                 (message, channel) => OnClientDataReceived.Invoke(message, FromKcpChannel(channel)),
-                () => OnClientDisconnected.Invoke(),
+                () => OnClientDisconnected?.Invoke(), // may be null in StopHost(): https://github.com/MirrorNetworking/Mirror/issues/3708
                 (error, reason) => OnClientError.Invoke(ToTransportError(error), reason),
                 config
             );