Migrate 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 up 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.

UNET Example

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”);
    }
}

Netcode for GameObjects Example

public class MyNetcodeExample : NetworkBehaviour
{
    public NetworkVariable<float> MyNetworkVariable = new NetworkVariable<float>();
    public override void OnNetworkSpawn()
    {
        ExampleClientRpc(10f);
        ExampleServerRpc(10f);
    }
    [Rpc(SendTo.Server)]
    public void ExampleServerRpc(float x)
    {
        Debug.Log(“Runs on server”);
    }
    [Rpc(SendTo.ClientsAndHost)]
    public void ExampleClientRpc(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.

UNET Example

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}.");
    }
}

Netcode for GameObjects Example

// Don't forget to initialize NetworkVariable with a value.
public NetworkVariable<string> PlayerName = new NetworkVariable<string>();

public NetworkVariable<int> Health = new NetworkVariable<int>(42);

// This how you update the value of a NetworkVariable, you can also use .Value to access the current value of a NetworkVariable.
void MyUpdate()
{
    Health.Value += 30;
}


void Awake()
{
  // Call this is in Awake or Start to subscribe to changes of the NetworkVariable.
    Health.OnValueChanged += OnChangeHealth;
}

void OnChangeHealth(int oldHealth, int newHealth){
    //There is no need anymore to manually assign the value of the variable here with Netcode. This is done automatically by Netcode for you.
    Debug.Log($"My new health is {newHealth}. Before my health was {oldHealth}");
}

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.

UNET Example

public int Health = 42;

public void Update(){
  Health++;
}

Netcode for GameObjects Example

public NetworkVariable<int> Health = new NetworkVariable<int>(42);

public void Update(){
  Health.Value = Health.Value + 1;
}

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.

UNET Example

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;
}

Netcode for GameObjects Example

NetworkList<int> m_ints = new NetworkList<int>();

// Call this is in Awake or Start to subscribe to changes of the NetworkList.
void ListenChanges()
{
    m_ints.OnListChanged += OnIntChanged;
}

// The NetworkListEvent has information about the operation and index of the change.
void OnIntChanged(NetworkListEvent<int> changeEvent)
{

}

Replace Command/ClientRPC

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

UNET Example

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

Netcode for GameObjects Example

    [Rpc(SendTo.Server)]
    public void ExampleServerRpc(float x)
    {
        Debug.Log(“Runs on server”);
    }
    [Rpc(SendTo.ClientsAndHost)]
    public void ExampleClientRpc(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.

UNET Example

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);
    }
}

Netcode for GameObjects Example

Server-only example:

using Unity.Netcode;

private void Setup()
{
    NetworkManager.Singleton.ConnectionApprovalCallback += ApprovalCheck;
    NetworkManager.Singleton.StartHost();
}

private void ApprovalCheck(byte[] connectionData, ulong clientId, NetworkManager.ConnectionApprovedDelegate callback)
{
    //Your logic here
    bool approve = true;
    bool createPlayerObject = true;

    // The Prefab hash. Use null to use the default player prefab
    // If using this hash, replace "MyPrefabHashGenerator" with the name of a Prefab added to the NetworkPrefabs field of your NetworkManager object in the scene
    ulong? prefabHash = NetworkpawnManager.GetPrefabHashFromGenerator("MyPrefabHashGenerator");

    //If approve is true, the connection gets added. If it's false. The client gets disconnected
    callback(createPlayerObject, prefabHash, approve, positionToSpawnAt, rotationToSpawnWith);
}

See Connection Approval for more information.

Replace NetworkServer.Spawn with NetworkObject.Spawn

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

UNET Example

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);
    }
}

Netcode for GameObjects Example

GameObject go = Instantiate(myPrefab, Vector3.zero, Quaternion.identity);
go.GetComponent<NetworkObject>().Spawn();

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.

UNET Example

public override bool OnCheckObserver(NetworkConnection conn)
{
 return IsvisibleToPlayer(getComponent<NetworkIdentity>(), coon);
}

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

Netcode for GameObjects Example

public void Start(){
    NetworkObject.CheckObjectVisibility = ((clientId) => {
        return IsVisibleToPlayer(NetworkObject, NetworkManager.Singleton.ConnectedClients[clientId]);
    });
}

public bool IsVisibleToPlayer(NetworkObject networkObject, NetworkClient client){
    // 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.

UNET Example

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

Netcode for GameObjects Example

public void ChangeScene()
{
    NetworkSceneManager.LoadScene("MyNewScene", LoadSceneMode.Single);
}

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.

UNET Example

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

Netcode for GameObjects Example

public void MyClientOnlyFunction()
{
    if (!IsClient) { return; }

    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.

UNET Example

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

    [SyncEvent]
    public event TakeDamageDelegate EventTakeDamage;

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

Netcode for GameObjects Example

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

    public event TakeDamageDelegate EventTakeDamage;

    [Rpc(SendTo.Server)]
    public void TakeDamageServerRpc(int val)
    {
        EventTakeDamage(val);
        OnTakeDamageClientRpc(val);
    }

    [Rpc(SendTo.ClientsAndHost)]
    public void OnTakeDamageClientRpc(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:

• Consider using the Hello World and Golden Path series to learn some basics of Netcode for GameObjects.
• Explore the educational samples content for a deeper exploration into Netcode for GameObjects:
  • Boss Room
  • 2D Spaceshooter Bitesize sample
  • Invaders Bitesize sample
  • Client-Driven Bitesize sample