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MLAPI In-Development Release Notes

The following in-progress content tracks features, updates, bug fixes, and refactoring for the next release of Unity MLAPI. Specific release information including supported Unity versions, release date, and release version is to be announced. All content and development information is subject to change.

In-Development Information

The following release notes document in-progress features, changes, bug fixes, and more for MLAPI. This content tracks on-going work in the develop branch of MLAPI. Finalized release notes will be built from this content for a future release of Unity MLAPI.


Unity MLAPI supports Windows and MacOS versions of Unity Editor and Player.

New features#

This release provides the following new features and APIs:

  • Snapshot features are in-progress for Unity MLAPI. Additional information will be provided during development.
  • Additional Profiler features are in-progress for performance network profiling. Additional information will be provided during development.

New APIs#

The following APIs have been added:

  • The following APIs support Profiler features:

    • MLAPI.Profiling.ProfilerNotifier
    • MLAPI.Profiling.ProfilerNotifier.NoTickDataHandler
    • MLAPI.Profiling.ProfilerNotifier.PerformanceDataEventHandler
  • The following APIs provide a simplified method of notifying when all clients have loaded to a new scene and are ready. The NetworkSceneManager captures events and provides that data without needing to re-subscribe.

    • MLAPI.SceneManagement.NetworkSceneManager.NotifyClientAllClientsLoadedSceneDelegate
    • MLAPI.SceneManagement.NetworkSceneManager.NotifyServerAllClientsLoadedSceneDelegate
    • MLAPI.SceneManagement.NetworkSceneManager.NotifyServerClientLoadedSceneDelegate
  • MLAPI.SnapshotSystem added for snapshot features.

  • The following APIs were created in refactoring custom spawn and destroy handlers for NetworkSpawnManager and usage of UnityEditor.GlobalObjectID. Custom spawn and destroy functionality is not affected, a server can still spawn a specific prefab and a different, predetermined prefab in its place on a client.

    • MLAPI.Spawning.INetworkPrefabInstanceHandler
    • MLAPI.Spawning.NetworkPrefabHandler


This release includes the following updates:

  • NetworkPrefabs updated to use GlobalObjectIdHash (internal Unity value) to best identify and link NetworkPrefabs in the project attached to NetworkManager between server and clients. The usage of GlobalObjectId including the following changes:

    • NetworkInstanceId was removed in favor of GlobalObjectIdHash, which is not exposed to public APIs. GlobalObjectIdHash is meant for MLAPI framework internals (specifically NetworkObject and NetworkPrefab linking layer) and is not intended for users.
    • When a NetworkPrefab is registered with NetworkManager, it can be spawned dynamically on the network at runtime. The server assigns a unique ID, and replicates it to connected clients for synchronization. This removes the need for UsePrefabSync (removed).
    • Custom spawn and destroy APIs were refactored without affecting functionality.
  • Completed code maintenance and updates to better support testing.

Removed APIs#

The following APIs have been removed due to refactoring:

  • MLAPI.Configuration.NetworkPrefab
  • MLAPI.NetworkManager.PerformanceDataEventHandler
  • MLAPI.Profiling.Sample
  • MLAPI.Spawning.NetworkSpawnManager.DestroyHandlerDelegate
  • MLAPI.Spawning.NetworkSpawnManager.SpawnHandlerDelegate
  • UsePrefabSync, PrefabHash, and PrefabHashGenerator
  • NetworkInstanceId and NetworkScenePostProcessor


This release includes the following issue fixes:

  • GitHub 367: OnClientConnectedCallback is now properly called when StartHost is called. This affects NetworkManager OnClientConnectedCallback and ConnectionApproval ConnectionApprovalCallback.
  • GitHub 664: Updates the drawElementCallback to assure there is only one default player prefab. This resolves an issue where adding a new Prefab in NetworkPrefabs automatically marked it as default.
  • GitHub 803 : Switched from ModuleDefinition.Types to ModuleDefinition.GetTypes() API. NetworkBehaviourILPP now iterates over all types and filters for NetworkBehaviour derived types and leaving no one outside from ILPP.