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Version: 1.8.1

Migrating from UNet to Netcode for GameObjects

UNet is deprecated and no longer supported. Follow this guide to migrate from UNet to Netcode for GameObjects. If you need help, contact us in the Unity Multiplayer Networking Discord.

Comparison between Netcode for GameObjects and UNet​

There are some differences between UNet and Netcode for GameObjects that you should be aware of as part of your migration:

  • Naming constraints may cause issues. UNet prefixed methods with Cmd or Rpc, whereas Netcode requires postfix. This may require either complicated multi-line regex to find and replace, or manual updates. For example, CommandAttribute has been replaced with RpcAttribute(SendTo.Server) and ClientRPCAttribute has been replaced with RpcAttribute(SendTo.NotServer) or RpcAttribute(SendTo.ClientsAndHost), depending on whether you want the host client to receive the RPC.
  • Errors for RPC postfix naming patterns don't show in your IDE.
  • Client and server have separate representations in UNet. UNet has a number of callbacks that don't exist in Netcode for GameObjects.
  • Prefabs need to be added to the Prefab registration list in Netcode for GameObjects.
  • Matchmaking isn't available in Netcode for GameObjects at this time.

Back p your project​

It's strongly recommended that you back up your existing UNet project before migration. You can do one or both of the following:

  • Create a copy of your entire project folder.
  • Use source control software, like Git.

Install Netcode for GameObjects and restart Unity​

Follow the installation guide to install Netcode for GameObjects.

Installing Netcode for GameObjects also installs some other packages such as Unity Transport, Unity Collections, and Unity Burst.

RPC Invoking​

Invoking an RPC works the same way as in UNet. Just call the function and it will send an RPC.

Replace NetworkIdentity with NetworkObject​

UNet’s NetworkIdentity is called NetworkObject in Netcode for GameObjects and works in a similar way.

Replace UNet NetworkTransform with Netcode NetworkTransform​

UNet’s NetworkTransform is also called NetworkTransform in Netcode for GameObjects and works in a similar way.

NetworkTransform doesn't have full feature parity with UNET's NetworkTransform. It lacks features like position synchronizing for rigid bodies.

Replace UNet NetworkAnimator with Netcode NetworkAnimator​

Replace UNet's NetworkAnimator with Netcode for GameObjects' NetworkAnimator component everywhere in your project.

Update NetworkBehaviour​

Replace UNet NetworkBehaviour with Netcode for GameObjects' NetworkBehaviour everywhere in your project.

public class MyUnetClass : NetworkBehaviour
{
    [SyncVar]
    public float MySyncFloat;
    public void Start()
    {
        if (isClient)
        {
            CmdExample(10f);
        }
        else if (isServer)
        {
            RpcExample(10f);
        }
    }
    [Command]
    public void CmdExample(float x)
    {
        Debug.Log(“Runs on server”);
    }
    [ClientRpc]
    public void RpcExample(float x)
    {
        Debug.Log(“Runs on clients”);
    }
}

See NetworkBehaviour for more information.

Replace SyncVar​

Replace SyncVar with NetworkVariable everywhere in your project.

To achieve equivalent functionality to SyncVar, hooks in Netcode for GameObjects subscribe a function to the OnValueChanged callback of the NetworkVariable. A notable difference between UNet hooks and Netcode for GameObjects' OnValueChanged callback is that Netcode for GameObjects gives you both the old and the newly changed value, while UNet only provides you with the old value. With UNet, you also had to manually assign the value of the SyncVar.

public class SpaceShip : NetworkBehaviour
{
    [SyncVar]
    public string PlayerName;


    [SyncVar(hook = "OnChangeHealth"))]
    public int Health = 42;

    void OnChangeHealth(int newHealth){
        Health = newHealth; //This is no longer necessary in Netcode.
        Debug.Log($"My new health is {newHealth}.");
    }
}

Replace all postfix increment and decrement usages of SyncVar in your project. Netcode's NetworkVariable.Value exposes a value type that's why postfix increment/decrement isn't supported.


public int Health = 42;

public void Update(){
  Health++;
}


See NetworkVariable for more information.

Replace SyncList with NetworkList​

Replace SyncList<T> with NetworkList<T> everywhere in your project. NetworkList has an OnListChanged event which is similar to UNet's Callback.

public SyncListInt m_ints = new SyncListInt();

private void OnIntChanged(SyncListInt.Operation op, int index)
{
    Debug.Log("list changed " + op);
}


public override void OnStartClient()
{
    m_ints.Callback = OnIntChanged;
}

Replace Command/ClientRPC​

UNet's Command/ClientRPC is replaced with Server/ClientRpc in Netcode for GameObjects, which works in a similar way.

    [Command]
    public void CmdExample(float x)
    {
        Debug.Log(“Runs on server”);
    }
    [ClientRpc]
    public void RpcExample(float x)
    {
        Debug.Log(“Runs on clients”);
    }
note

In Netcode for GameObjects, RPC function names must end with an Rpc suffix.

See Messaging System for more information.

Replace OnServerAddPlayer​

Replace OnServerAddPlayer with ConnectionApproval everywhere in your project.

using UnityEngine;
using UnityEngine.Networking;
using UnityEngine.Networking.NetworkSystem;

class MyManager : NetworkManager
{
    public override void OnServerAddPlayer(NetworkConnection conn, short playerControllerId, NetworkReader extraMessageReader)
    {
        if (extraMessageReader != null)
        {
            var s = extraMessageReader.ReadMessage<StringMessage>();
            Debug.Log("my name is " + s.value);
        }
        OnServerAddPlayer(conn, playerControllerId, extraMessageReader);
    }
}

See Connection Approval for more information.

Replace NetworkServer.Spawn with NetworkObject.Spawn​

Replace NetworkServer.Spawn with NetworkObject.Spawn everywhere in your project.


using UnityEngine;
using UnityEngine.Networking;

public class Example : NetworkBehaviour
{
    //Assign the Prefab in the Inspector
    public GameObject m_MyGameObject;
    GameObject m_MyInstantiated;

    void Start()
    {
        //Instantiate the prefab
        m_MyInstantiated = Instantiate(m_MyGameObject);
        //Spawn the GameObject you assign in the Inspector
        NetworkServer.Spawn(m_MyInstantiated);
    }
}

See Object Spawning for more information.

Custom Spawn Handlers​

Netcode has Custom Spawn Handlers to replace UNet's Custom Spawn Functions. See Object Pooling for more information.

Replace NetworkContextProperties​

Netcode has IsLocalPlayer, IsClient, IsServer, and IsHost to replace UNet's isLocalPlayer, isClient, and isServer. In Netcode for GameObjects, each object can be owned by a specific peer. This can be checked with IsOwner, which is similar to UNet's hasAuthority.

NetworkProximityChecker, OnCheckObserver and network visibility​

Netcode for GameObjects doesn't have direct equivalents for the following UNet components and functions:

  • NetworkPromimityChecker component. Network visibility for clients works similar as in UNet.
  • ObjectHide message. In Netcode for GameObjects, networked objects on the host are always visible.
  • OnSetLocalVisibility function. A manual network proximity implementation with the OnCheckObserver can be ported to Netcode for GameObjects by using NetworkObject.CheckObjectVisibility.
  • OnRebuildObservers isn't needed for the Netcode for GameObjects' visibility system.
public override bool OnCheckObserver(NetworkConnection conn)
{
 return IsvisibleToPlayer(getComponent<NetworkIdentity>(), coon);
}

public bool IsVisibleToPlayer(NetworkIdentity identity, NetworkConnection conn){
    // Any promimity function.
    return true;
}

See Object Visbility to learn more about Netcodes network visiblity check.

Update scene management​

In Netcode for Gameobjects, scene management isn't done using the NetworkManager like in UNet. The NetworkSceneManager provides equivalent functionality for switching scenes.

public void ChangeScene()
{
    MyNetworkManager.ServerChangeScene("MyNewScene");
}

Update ClientAttribute/ClientCallbackAttribute and ServerAttribute/ServerCallbackAttribute​

Netcode for GameObjects currently doesn't offer a replacement for marking a function with an attribute so that it only runs on the server or the client. You can manually return out of the function instead.

[Client]
public void MyClientOnlyFunction()
{
    Debug.Log("I'm a client!");
}

Replace SyncEvent with an RPC event​

Netcode for GameObjects doesn't provide an equivalent for SyncEvent. To port SyncEvent code from UNet to Netcode for GameObjects, send an RPC to invoke the event on the other side.

public class DamageClass : NetworkBehaviour
{
    public delegate void TakeDamageDelegate(int amount);

    [SyncEvent]
    public event TakeDamageDelegate EventTakeDamage;

    [Command]
    public void CmdTakeDamage(int val)
    {
        EventTakeDamage(val);
    }
}

Network Discovery​

Netcode for GameObjects doesn't provide Network Discovery. The Contributions repository provides an example implementation for NetworkDiscovery.

Next steps​

After migrating to the Netcode for GameObjects package, you can review the following for what to do next: