Update

Assets/Scripts/Network/BasicSpawner.cs

@@ -72,8 +72,13 @@ namespace Hallucinate.UI
                         await _runner.Shutdown();
                     }
 
-                    Debug.Log("[BasicSpawner] Destroying existing runner component.");
-                    Destroy(_runner);
+                    // Check if it still exists (Unity pseudo-null check)
+                    if (_runner != null)
+                    {
+                        // Only log if it's actually a valid object to destroy
+                        // If it's already marked for destruction, Unity == null will be true soon
+                        Destroy(_runner);
+                    }
                     _runner = null;
 
                     await Task.Yield();
@@ -84,6 +89,8 @@ namespace Hallucinate.UI
                 }
             }
 
+            if (this == null) return; // BasicSpawner itself might be destroyed
+
             Debug.Log("[BasicSpawner] Creating new NetworkRunner component.");
             _runner = gameObject.AddComponent<NetworkRunner>();
             _runner.ProvideInput = true;
@@ -118,7 +125,12 @@ namespace Hallucinate.UI
 
         public async Task<bool> StartHost(string sessionName, string displayName, string password = null)
         {
-            if (_isStarting) return false;
+            // Wait for any existing startup process (like StartLobby) to finish
+            while (_isStarting)
+            {
+                await Task.Yield();
+            }
+
             _isStarting = true;
 
             try 

Assets/Scripts/Network/PlayerDataManager.cs

@@ -24,15 +24,22 @@ public class PlayerDataManager : NetworkBehaviour
         Instance = this;
     }
 
+    public override void Despawned(NetworkRunner runner, bool hasState)
+    {
+        if (Instance == this) Instance = null;
+    }
+
     [Rpc(RpcSources.All, RpcTargets.StateAuthority)]
     public void RPC_UpdatePlayerMetaData(PlayerRef playerRef, _PlayerMetaData metaData)
     {
+        if (Object == null || !Object.IsValid) return;
         Players.Set(playerRef, metaData);
     }
 
     [Rpc(RpcSources.All, RpcTargets.StateAuthority)]
     public void RPC_SetReady(PlayerRef playerRef, bool ready)
     {
+        if (Object == null || !Object.IsValid) return;
         if (Players.TryGet(playerRef, out var data))
         {
             data.IsReady = ready;
@@ -48,6 +55,10 @@ public class PlayerDataManager : NetworkBehaviour
     
     public bool TryGetPlayerMetaData(PlayerRef playerRef, out _PlayerMetaData metaData)
     {
+        metaData = default;
+        // Kiểm tra xem object đã được Spawned chưa trước khi truy cập networked property
+        if (Object == null || !Object.IsValid) return false;
+        
         return Players.TryGet(playerRef, out metaData);
     }
 }