Migrating from UNet to Netcode for GameObjects

Use this step-by-step guide to migrate your projects from Unity UNet to Netcode for GameObjects (Netcode). If you need help, contact us in the Unity Multiplayer Networking Discord.

UNet Deprecation

UNet is an entirely deprecated product, and you should upgrade to Netcode for GameObjects as soon as possible.

Current limitations

Review the following limitations for upgrade and migrations from previous versions of Unity UNet to Netcode:

• Naming constraints may cause issues. UNet prefixed methods with Cmd or Rpc. Netcode requires postfix. This may require either complicated multi-line regex to find and replace, or manual updates. For example, CommandAttribute has been renamed ServerRpcAttribute and ClientRPCAttribute has been renamed ClientRpcAttribute.
• 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 for Netcode.
• Prefabs need to be added to the Prefab registration list for Netcode.
• Matchmaking isn't available in Netcode at this time.

Backup your project

It is recommended that you back up your project before proceeding with the migration. For example:

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

bestpractice

We recommend using both methods to backup your project. This gives you a copied project and tracking through committed changes and history.

Install Netcode and restart Unity

See the Netcode installation guide for more information.

note

If you install Git for the first time, you will need to restart your system.

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 and works in a similar way.

Replace UNet NetworkTransform with Netcode NetworkTransform

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

The NetworkTransform does not have full feature parity with UNET's NetworkTransform. It lacks features like position synchronizing for rigidbodies.

Replace UNet NetworkAnimator with Netcode NetworkAnimator

Replace UNEt's NetworkAnimator with Netcode's NetworkAnimator component everywhere in your project.

Update NetworkBehaviour

Replace UNet NetworkBehaviour with Netcode's 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);
    }
    [ServerRpc]
    public void ExampleServerRpc(float x)
    {
        Debug.Log(“Runs on server”);
    }
    [ClientRpc]
    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 of SyncVar hooks in Netcode subscribe a function to the OnValueChanged callback of the NetworkVariable. A noteable difference between the UNet hooks and Netcode's OnValueChanged callback is that Netcode gives you both the old and the newly changed value while UNet provides you only 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 a 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 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

    [ServerRPC]
    public void ExampleServerRpc(float x)
    {
        Debug.Log(“Runs on server”);
    }
    [ClientRPC]
    public void ExampleClientRpc(float x)
    {
        Debug.Log(“Runs on clients”);
    }

note

In Netcode, RPC function names must end with a ClientRpc/ServerRpc 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 UNets isLocalPlayer, isClient and isServer. In Netcode each object can be owned by a specific peer. This can be checked with IsOwner which is similar to UNets hasAuthority.

Network Proximity Checker/ OnCheckObserver with Netcode visibility

There is no direct equivalent to the NetworkPromimityChecker UNet component in Netcode. Network visiblilty for clients works similar as in UNet. Netcode does not have an equivalent to the ObjectHide message from UNet. In Netcode networked objects on the host are always visible. There is no equivalent to the OnSetLocalVisibility function in UNet. A manual network promiximty implementation with the OnCheckObserver can be ported to Netcode by using NetworkObject.CheckObjectVisibility. OnRebuildObservers isn't needed for Netcode visibilty 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 SceneManagement

In Netcode, scene management isn't done over 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 currently does not 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 RPC event

Netcode does not provide an equivalent for SyncEvent. To port SyncEvent code from UNet to Netcode, 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;

    [ServerRpc]
    public void TakeDamageServerRpc(int val)
    {
        EventTakeDamage(val);
        OnTakeDamageClientRpc(val);
    }

    [ClientRpc]
    public void OnTakeDamageClientRpc(int val){
        EventTakeDamage(val);
    }
}

Network Discovery

Netcode does not provide Network Discovery. The Contributions repository provides an example implementation for NetworkDiscovery.

Next Steps

After migrating and updating to the Netcode package, we recommend looking into the following:

• 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