Release Notes

3.0.0

Preview

Build 1495 (Jul 29, 2026)

Breaking Changes

Removed UFusionOnlineSubsystem::SetPriority(), use UFusionActorComponent::SetLocalSendRate() / SetRoomSendRate() instead
Removed unnecessary UFusionOnlineSubsystem::GetResolvedOwner(), use UFusionOnlineSubsystem::GetOwner() instead. Existing Blueprints migrate automatically via a CoreRedirect
Remove OnConnectedToPhoton multicast delegate on UFusionOnlineSubsystem that was not firing properly. Bind to OnSuccess when connecting in order to trigger logic after connecting to Photon
Removed UFusionHelpers::FusionClientTravel(). Use UFusionOnlineSubsystem::ClientTravel(), ChangeWorld() or ChangeWorldByName() instead
OnForcedDisconnect now also returns a reason enum

What's New

Unreal 5.8 support

Improvements

Add the ability to adjust object SendRate via methods on the FusionActorComponent (SetLocalSendRate() / SetRoomSendRate()). Adjusting the local send rate can be used with the Dynamic ownership model to react quickly while wanting ownership
Add the OnObjectOwnerPredictionFailed delegate on the UFusionActorComponent that can be used to respond to instances when ownership was not received in Dynamic ownership mode
Rework ownership request/response system. New method: RespondToOwnershipRequest. New events: OnOwnershipDenied, OnOwnershipRequested. Requests are automatically denied when nothing is bound to OnOwnershipRequested
Add error log and soft assert to hash collisions
Avoid costly copies of FFusionObjectActorPair
Support sublevel streaming
APlayerState no longer has a custom lifespan when changing world, lifecycle is owned by Unreal's own travelling logic
Changed ObjectId counter to uint64, removes chance of hash collisions when dealing with a large number of networked map actors

Changes

Move RPC Blueprint Node into its own "UncookedOnly" Module. Leave rest in a pure "Editor" module

Bug Fixes

Fixed: Compile warning from a Unreal header when compiling 5.7 in Visual Studio 2026 with MSVC 14.51+ being treated as an error
Fixed: Issue where PlayerState was reported as being a duplicate
Fixed: Actor roles were not reset back to ROLE_Authority after shutting down Fusion. Actors should now have normal offline behaviour once Fusion is torn down
Fixed: Remove unused Forecast Physics setting: MaxSpawnExtrapolationTime
Fixed: Forecast Physics objects could spawn in the wrong position (underground or invisible) for remote clients until the owning client first moved them. Fast-moving objects may now spawn a fraction behind their predicted position for a frame before correcting
Fixed: UniqueNetId used by Steam and other online subsystems is now properly replicated
Fixed: Disconnecting from inside RPC will now cause a controlled shutdown, ending current tick and object iteration
Fixed: Failing to create networked subobjects caused a memory leak, will now revert creation and prevent the leak
Fixed: Non-networked components of networked actors were incorrectly encoded and failed to replicate

Build 1341 (Jun 08, 2026)

What's New

FilterPlugin.ini is now included in the packaged plugin

Changes

UHT plugin doesnt auto detect engine version anymore and instead uses a hard coded value

Build 1315 (Jun 01, 2026)

What's New

LICENSE.txt and THIRD_PARTY_NOTICES.txt with the Fusion Unreal license as well as licenses from third party libraries Fusion Unreal uses

Build 1254 (May 15, 2026)

Improvements

Add the ability to disable GameState replication via CVAR
Performance improvements related to updating actor state

Build 1214 (May 07, 2026)

Bug Fixes

Fixed: Issue preventing streaming levels from being unloaded

Build 1201 (May 05, 2026)

Breaking Changes

Renamed SharedMode namespace to FusionCore
A number of .cpp and .h files have been renamed to add the "Fusion" prefix. CoreRedirects exist for BP/Asset references, but existing code files will need to be updated
StartFusionSession is no longer exposed as a BP function and is instead called automatically from the BP functions to create/join rooms

Improvements

StartFusionSession on subsystem no longer async, can also be accessed using static class FusionMatchmakingHelpers
Implement the new initial map logic, where its part of room options
Remove RPC predefined array size
GameState now networked implicitly
GameState ReplicatedWorldTimeSeconds uses Fusions own network time
Network Debugging Tool, found under: Window/Fusion Debug Tools

Bug Fixes

Fixed: Map attach issues
Fixed: Better handling for blueprint RPC property creation
Fixed: Issue where Fusion matchmaking callbacks could be cleaned up prematurely when another PIE window World is destroyed
Fixed: Possible build failure when creating Fusion RPCs
Fixed: Prevent possible timeout disconnection error (1041) when loading into a map in standalone mode
Fixed: Potential crash when switching maps
Fixed: Cloning properties in UHT uses more DRY logic and should support most types now
Fixed: Ensure FName can be sent as parameters in rpcs, worked nested in structs before
Fixed: Setting softobjectreference to null caused crash, fixed
Fixed: Patch objectid changes (map changes) resulted in incorrectly serialized objectids
Fixed: Remove redundant call to destroy, just causes incorrect logspam "not authority to destroy"
Fixed: Make sure we flag individual destroy instead
Fixed: Ensure we only send the events when replication inside fusion is active
Fixed: Replication issue with PlayerState actors

Build 1118 (Apr 20, 2026)

Improvements

Add the ability to set the "Local State Copy Mode" of an actor to "Manual" in order to prevent potentially expensive copy operations every frame for an actor the client can modify. Using this mode found on the UFusionActorComponent requires the user to call UFusionActorComponent::CopyLocalStateNextFrame() in order to trigger a copy of the state of an Actor next frame. Copying the state of the actor allows other connected clients to receive the replicated changes
Performance improvements related to detecting transient objects

Build 1112 (Apr 16, 2026)

Improvements

Performance improvements in the core Fusion library related to strings

Bug Fixes

Fixed: Issue where StartFusionSession() with a valid InitialWorld would not trigger a map load

Build 1108 (Apr 13, 2026)

Improvements

Performance improvements in the core Fusion library. Including working with strings and ownership methods

Bug Fixes

Fixed: Sub objects would trigger unnecessary data to be sent

Build 1100 (Mar 25, 2026)

Bug Fixes

Fixed: Replication issue with PlayerState actors

Build 1088 (Mar 24, 2026)

Breaking Changes

Renamed: UFusionActorSettings to UFusionActorComponent

Changes

Trying to connect while being connected is failing the connecting instead of tearing down the session and starting a new one
Trying to join a room while being in a room is failing the joining instead of tearing down the session and starting a new one
Added ClientTravel to FusionSubsystem, this is to handle map transitions when running under one process, this is a known unreal bug

Bug Fixes

Fixed: Region Select Mode "Select" was timing out
Fixed: Issues with AttachCurrentMap, ensure connecting clients (none master) are put into correct state before attaching
Fixed: Make sure we clear all related objects in OnMapDestroy
Fixed: Add missing rpc type handlers, caused a crash
Fixed: Make sure APlayerState is properly replicated and survives map transitions

Build 1011 (Mar 12, 2026)

Previous SDK versions are no longer compatible with deployed infrastructure. Please update to this build or later

Breaking Changes

FFusionRoomOptions does not have an InitialWorld property anymore, set the InitialWorld when calling UFusionOnlineSubsystem::StartFusionSession()
EActionFailureCodes changed and numeric values for enums changed
UFusionClient::IsConnected() was removed, use UFusionOnlineSubsystem::IsConnected() or UFusionRealtimeClient::IsConnected() instead
FTimerState was renamed to FFusionTimerState and was moved to FFusionTimerState.h
The SharedMode::Logging namespace is now in the PhotonCommon namespace
The SharedMode::CharType and SharedMode::StringType types are now both in the PhotonCommon namespace
Update plugin code to follow Epics guidelines
Removed unused RoomName Argument from JoinRandomRoom

What's New

A new Realtime Matchmaking API was added that replaces the old connection methods, providing full access to Photon Realtime related features
A LeaveRoom blueprint node was added to leave a Realtime room without disconnecting
Added support for dynamically adding and removing replicated actor components
Improved AOI system
Added a new "Player Attached" ownership mode which means the player actor will be destroyed when they disconnect
Ability to connect ongoing world to fusion via UFusionOnlineSubsystem::AttachCurrentMap()

Changes

The Fusion Session is not started automatically when joining a Realtime room anymore, call UFusionOnlineSubsystem::StartFusionSession() to start a Fusion Session after joining a room

Bug Fixes

Fixed: Prevent erroneous error logs being generated when the non-master client code loads the map via the OnMapLoadPerform callback
Fixed: Uninitialized memory caused the frame update to never run
Fixed: Class properties when used in RPCs
Fixed: Ensure InitialMap loads properly
Fixed: Update service while in shutdown to allow us to receive the disconnect status
Fixed: Harden disconnect
Fixed: Add physics state delta checks to avoid unnecessary network sends
Fixed: Potential issue when using "Standalone Game" launched from the editor
Fixed: Potential crash and log spam when leaving a Photon room

Build 835 (Feb 19, 2026)

Bug Fixes

Fixed: Closing a standalone window sometimes caused a crash
Fixed: A player would sometimes fail to spawn properly after joining a room at start-up in Unreal 5.4

Build 760 (Feb 12, 2026)

Bug Fixes

Fixed: Adjust a number of Fusion Blueprint nodes so that the main input parameter defaults to self as they did previously: HasOwner, GetOwner, GetResolvedOwner, IsOwner, CanModify
Fixed: Fix issue where remote Pawns were being assigned the local PlayerController. Remote Pawns no longer have a PlayerController set

Build 756 (Feb 11, 2026)

Bug Fixes

Fixed: Fix closing PIE instance crash
Fixed: Fix issues in seamless travel

Build 720 (Feb 10, 2026)

Breaking Changes

Correct spelling of "Recieve" to be "Receive" for Fusion RPC functions. Fusion C++ RPC functions need to be renamed from *_Recieve to *_Receive
Previous SDK versions are no longer compatible with deployed infrastructure. Please update to this (build 719) or later.

What's New

Add support for using Actors, Objects, Classes as RPC parameters
Connecting to the Photon Cloud supports now choosing the best region based on the players ping
All edge cases around object life cycles should be solved to provide more consistent replication
Android support and crossplay support between Android and Windows
Removed interpolation of replicated properties, the behaviour of Fusion now matches unreals netcode more closely in several regards.
Property RepNotify's now supports previous value argument.
Native remote function calls now supported in both blueprint and c++, see documentation for further details. RPCs In Depth

Improvements

Improved physics prediction and replication further
All public code should now conform to the unreal formatting standard
Fusion can now use "Run Under One Process" mode in unreal editor

Bug Fixes

Fixed: Fix issue where a client may not be reliably informed of an object having its owner removed
Fixed: Fix a potential issue where an actor would not be properly replicated if it is part of a map and immediately possessed
Fixed: Prevent an assert triggering when loading into level when using UE 5.4.4
Fixed: Manually set netdriver world
Fixed: Issue with map loading when loading the same map again
Fixed: Map actors now use a consistent hashing for identifying sub components which removes the need for consistent component order on all connected clients.

Build 492 (Jan 12, 2026)

What's New

Unreal 5.7 support

Bug Fixes

Fixed: Native pointer usage in member declaration preventing a shipping build

Build 438 (Dec 18, 2025)

Breaking Changes

Previous SDK versions are no longer compatible with deployed infrastructure. Please update to this (build 438) or later.

What's New

Added full support for the Character Movement Component
Added internal "string heap" replication system for string and text data
Added support for networking GameInstance and calling Fusion RPCs on it
The Actor Role now reports to be either Authority or SimulatedProxy based on whether it can be modified
The NetMode now reports to be a Client

Improvements

Object replication model has been updated to reduce bandwidth and improve type support

Bug Fixes

Fixed: Issue where a replicated Actor reference set to None/nullptr by the authority would not be correctly set on remote clients
Fixed: Duplicate CreatedLocal existed on derived RootObject, hiding other implementation
Fixed: RPC regression fix, datatypes not properly serialized
Fixed: IsOwner and CanModify was not properly evaluating all conditional branches
Fixed: Race condition on sub-object system during object destruction

Build 354 (Nov 25, 2025)

Bug Fixes

Fixed: Prevent crash and add error log when running multiple PIE windows in one process

Build 349 (Nov 24, 2025)

Initial release

3.0.0

Preview