# Multiplayer & Networking **URL:** https://forums.unrealengine.com/c/development-discussion/programming-scripting/multiplayer-networking/132.md [Latest](https://forums.unrealengine.com/latest.md) · [Categories](https://forums.unrealengine.com/categories.md) · [Tags](https://forums.unrealengine.com/tags.md) --- ## [About the Multiplayer & Networking category](https://forums.unrealengine.com/t/about-the-multiplayer-networking-category/248560)
**Author:** [@SkyeEden](https://forums.unrealengine.com/u/SkyeEden)\ **Replies:** 0\ **Last updated:** [September 2, 2021, 1:57am UTC](https://forums.unrealengine.com/t/about-the-multiplayer-networking-category/248560 "2021-09-02T01:57:36Z")
Creating experiences to enjoy with your friends? This is the place to talk couch co-op, online multiplayer, and beyond! --- ## [Iris Networking UE5.7+ with FastArray Example](https://forums.unrealengine.com/t/iris-networking-ue5-7-with-fastarray-example/2684404)
**Author:** [@GXMark](https://forums.unrealengine.com/u/GXMark)\ **Replies:** 2\ **Last updated:** [November 10, 2026, 8:33pm UTC](https://forums.unrealengine.com/t/iris-networking-ue5-7-with-fastarray-example/2684404 "2026-11-10T20:33:28Z")
UE 5.7 (Source/Dist) Configuration The following steps are needed to use Iris: In unreal editor enable Iris Networking (Beta) Plugin ( Restart) Update UProject Check that the plugin has been added to uproject file "Pl… --- ## [Marking a FIrisFastArraySerializer item dirty does not get the object polled](https://forums.unrealengine.com/t/marking-a-firisfastarrayserializer-item-dirty-does-not-get-the-object-polled/2853441)
**Author:** [@ArnaudCUbi](https://forums.unrealengine.com/u/ArnaudCUbi)\ **Replies:** 0\ **Last updated:** [November 10, 2026, 4:43pm UTC](https://forums.unrealengine.com/t/marking-a-firisfastarrayserializer-item-dirty-does-not-get-the-object-polled/2853441 "2026-11-10T16:43:28Z")
Hi, I have an issue with using FIrisFastArraySerializer using the push model. I am on 5.7.4. When I call MarkItemDirty on one item, I expect the object to be polled asap ( because net.Iris.EnableForceNetUpdate is false… --- ## [\[Iris\] Warns/Ensures when streaming out actors that are initially replicating ](https://forums.unrealengine.com/t/iris-warns-ensures-when-streaming-out-actors-that-are-initially-replicating/2617732)
**Author:** [@anonymous-edc](https://forums.unrealengine.com/u/anonymous-edc)\ **Replies:** 2\ **Last updated:** [November 10, 2026, 8:53am UTC](https://forums.unrealengine.com/t/iris-warns-ensures-when-streaming-out-actors-that-are-initially-replicating/2617732 "2026-11-10T08:53:06Z")
This doesn’t happen every single time, so im not entirely sure what the state is that’s required to produce it, other than we have lots of actors, several of them stream in that have replication enabled. As sometimes hap… --- ## [IsLocallyControlled() in BeginPlay() with Iris Enabled](https://forums.unrealengine.com/t/islocallycontrolled-in-beginplay-with-iris-enabled/2703151)
**Author:** [@RaidenV\_00](https://forums.unrealengine.com/u/RaidenV_00)\ **Replies:** 2\ **Last updated:** [November 10, 2026, 6:58am UTC](https://forums.unrealengine.com/t/islocallycontrolled-in-beginplay-with-iris-enabled/2703151 "2026-11-10T06:58:49Z")
Hi, I encountered a problem when using Iris in UE5.6. I have many separate operations according to IsLocallyControlled() in BeginPlay(), such as if player is not locally controlled then he won’t create a widget on him. … --- ## [FNativeFastArrayReplication Fragment is missing HasFullPushBasedDirtiness trait](https://forums.unrealengine.com/t/fnativefastarrayreplication-fragment-is-missing-hasfullpushbaseddirtiness-trait/2707703)
**Author:** [@blackrock0700](https://forums.unrealengine.com/u/blackrock0700)\ **Replies:** 1\ **Last updated:** [November 9, 2026, 9:16pm UTC](https://forums.unrealengine.com/t/fnativefastarrayreplication-fragment-is-missing-hasfullpushbaseddirtiness-trait/2707703 "2026-11-09T21:16:13Z")
I found that FNativeFastArrayReplicationFragment is being polled every frame because its traits are set to HasPushBasedDirtiness instead of HasFullPushBasedDirtiness. This logic exists in FFastArrayReplicationFragmentBas… --- ## [MassAI Replication State in 5.7 and future roadmap?](https://forums.unrealengine.com/t/massai-replication-state-in-5-7-and-future-roadmap/2684012)
**Author:** [@anonymous-edc](https://forums.unrealengine.com/u/anonymous-edc)\ **Replies:** 11\ **Last updated:** [November 5, 2026, 9:12am UTC](https://forums.unrealengine.com/t/massai-replication-state-in-5-7-and-future-roadmap/2684012 "2026-11-05T09:12:58Z")
We are using 5.7 Preview to check out the latest MassAI implementation with StateTree and mostly replication support state. There are some major problems with replication the entities transform and Crowd LOD system. (us… --- ## [Ima Looking for a experienced Technical Partner, Not A Yes Man Or Woman Someone Who Will challenge My Ideas About the Game it self, ](https://forums.unrealengine.com/t/ima-looking-for-a-experienced-technical-partner-not-a-yes-man-or-woman-someone-who-will-challenge-my-ideas-about-the-game-it-self/2849614)
**Author:** [@Creator\_Cosmic](https://forums.unrealengine.com/u/Creator_Cosmic)\ **Replies:** 0\ **Last updated:** [November 3, 2026, 9:41pm UTC](https://forums.unrealengine.com/t/ima-looking-for-a-experienced-technical-partner-not-a-yes-man-or-woman-someone-who-will-challenge-my-ideas-about-the-game-it-self/2849614 "2026-11-03T21:41:34Z")
Welcome to COSMIC VOID :milky\_way: Welcome to the official community for COSMIC VOID, an original supernatural fantasy action RPG currently in development. This is where the world of COSMIC VOID comes to life. Explore … --- ## [\[Iris\] Crash for SubObject with only COND\_InitialOnly properties ](https://forums.unrealengine.com/t/iris-crash-for-subobject-with-only-cond-initialonly-properties/2570339)
**Author:** [@anonymous-edc](https://forums.unrealengine.com/u/anonymous-edc)\ **Replies:** 5\ **Last updated:** [November 3, 2026, 9:21am UTC](https://forums.unrealengine.com/t/iris-crash-for-subobject-with-only-cond-initialonly-properties/2570339 "2026-11-03T09:21:04Z")
Hello, we’ve run into an issue with SubObjects which only contain “InitialOnly” properties. When creating a SubObject which only contains replicating properties with the condition COND\_InitialOnly, we get a crash in FN… --- ## [Unable to serialize subobject's outer ](https://forums.unrealengine.com/t/unable-to-serialize-subobjects-outer/2543630)
**Author:** [@anonymous-edc](https://forums.unrealengine.com/u/anonymous-edc)\ **Replies:** 3\ **Last updated:** [November 3, 2026, 9:13am UTC](https://forums.unrealengine.com/t/unable-to-serialize-subobjects-outer/2543630 "2026-11-03T09:13:56Z")
We have a player pawn which owns a replicated components which owns a set of replicated subobjects. Sometimes those subobjects’ outers fail to resolve correctly. Rather than the replicated component, their outer is set t… --- ## [Spacewar Only works in Standalone mode, Game Build doesn't work](https://forums.unrealengine.com/t/spacewar-only-works-in-standalone-mode-game-build-doesnt-work/2846647)
**Author:** [@August831](https://forums.unrealengine.com/u/August831)\ **Replies:** 2\ **Last updated:** [October 30, 2026, 11:01pm UTC](https://forums.unrealengine.com/t/spacewar-only-works-in-standalone-mode-game-build-doesnt-work/2846647 "2026-10-30T23:01:14Z")
When I play the game through the editor in standalone mode, the game gets detected by steam as Spacewar, but when i build the game (whether it be Dev build or shipping) it doesnt detect the game, therefore multiplayer do… --- ## [Iris warning: “BroadcastLoadedModulesUpdated() called while there are N active ReplicationSystems”](https://forums.unrealengine.com/t/iris-warning-broadcastloadedmodulesupdated-called-while-there-are-n-active-replicationsystems/2847119)
**Author:** [@everything-bagel](https://forums.unrealengine.com/u/everything-bagel)\ **Replies:** 0\ **Last updated:** [October 30, 2026, 11:52am UTC](https://forums.unrealengine.com/t/iris-warning-broadcastloadedmodulesupdated-called-while-there-are-n-active-replicationsystems/2847119 "2026-10-30T11:52:44Z")
Has anyone seen the Iris Warning below? I’m trying to figure out if I should ignore it or if there is some bug from my project. I’ve scoured the internet and can’t find any information on it. In both 5.7 and 5.8 I see t… --- ## [Iris Replication System ](https://forums.unrealengine.com/t/iris-replication-system/2661726)
**Author:** [@Fin1kkk](https://forums.unrealengine.com/u/Fin1kkk)\ **Replies:** 1\ **Last updated:** [October 30, 2026, 11:40am UTC](https://forums.unrealengine.com/t/iris-replication-system/2661726 "2026-10-30T11:40:17Z")
Hello everyone, I recently watched an insightful Unreal Fest Orlando 2025 session about the development of Iris. My question is, how reliable is the system in the current experimental state? There’s more official docume… --- ## [Make static actor Iris replication failure non-fatal during WP cell unload ](https://forums.unrealengine.com/t/make-static-actor-iris-replication-failure-non-fatal-during-wp-cell-unload/2718054)
**Author:** [@anonymous-edc](https://forums.unrealengine.com/u/anonymous-edc)\ **Replies:** 4\ **Last updated:** [October 30, 2026, 11:37am UTC](https://forums.unrealengine.com/t/make-static-actor-iris-replication-failure-non-fatal-during-wp-cell-unload/2718054 "2026-10-30T11:37:37Z")
We found an replication issue described as follow, not sure if Epic has already found and fixed it: When a client unloads a World Partition cell while the server has in-flight replication data for a static actor in tha… --- ## [Assert triggered in Iris with FFastArraySerializer type combined with ReplicatedUsing ](https://forums.unrealengine.com/t/assert-triggered-in-iris-with-ffastarrayserializer-type-combined-with-replicatedusing/2678265)
**Author:** [@anonymous-edc](https://forums.unrealengine.com/u/anonymous-edc)\ **Replies:** 3\ **Last updated:** [October 30, 2026, 11:32am UTC](https://forums.unrealengine.com/t/assert-triggered-in-iris-with-ffastarrayserializer-type-combined-with-replicatedusing/2678265 "2026-10-30T11:32:17Z")
Hi, I’m seeing an issue where a replicating a type based on FFastArraySerializer in a UPROPERTY with ReplicatedUsing=OnRep\_Func asserts with Iris, in FFastArrayReplicationFragmentBase since the resultant replication fra… --- ## [Iris: Fast Array does not reliably remove items under certain conditions. ](https://forums.unrealengine.com/t/iris-fast-array-does-not-reliably-remove-items-under-certain-conditions/2666615)
**Author:** [@anonymous-edc](https://forums.unrealengine.com/u/anonymous-edc)\ **Replies:** 10\ **Last updated:** [October 30, 2026, 11:29am UTC](https://forums.unrealengine.com/t/iris-fast-array-does-not-reliably-remove-items-under-certain-conditions/2666615 "2026-10-30T11:29:40Z")
We are experiencing an issue where Fast Arrays do not reliably remove items that the Server has removed. This issue only manifests when using Iris replication, it does not occur when using “standard” replication. It also… --- ## [\[Iris\] Multiple Actors Having a Shared Sub-Object Dependency ](https://forums.unrealengine.com/t/iris-multiple-actors-having-a-shared-sub-object-dependency/2606452)
**Author:** [@anonymous-edc](https://forums.unrealengine.com/u/anonymous-edc)\ **Replies:** 7\ **Last updated:** [October 30, 2026, 11:24am UTC](https://forums.unrealengine.com/t/iris-multiple-actors-having-a-shared-sub-object-dependency/2606452 "2026-10-30T11:24:19Z")
A little background on how we got here I think is required, We’ve got a large shared inventory for the players. Each item is a unique UObject instance because it’s a lot easier to track state changes to a given object t… --- ## [Iris Replication of TWeakObjectPtr inside a struct ](https://forums.unrealengine.com/t/iris-replication-of-tweakobjectptr-inside-a-struct/2706941)
**Author:** [@anonymous-edc](https://forums.unrealengine.com/u/anonymous-edc)\ **Replies:** 5\ **Last updated:** [October 30, 2026, 11:21am UTC](https://forums.unrealengine.com/t/iris-replication-of-tweakobjectptr-inside-a-struct/2706941 "2026-10-30T11:21:34Z")
Hi, I have come across a nuance of Iris and would like to know if this is intentional or not, and subsequently what the intended pattern should be. If I replicate a TWeakObjectPtr inside an actor, this gets replicated… --- ## [Replicating FInstancedStruct with Iris](https://forums.unrealengine.com/t/replicating-finstancedstruct-with-iris/1948348)
**Author:** [@Nacho\_Abril](https://forums.unrealengine.com/u/Nacho_Abril)\ **Replies:** 1\ **Last updated:** [October 30, 2026, 11:18am UTC](https://forums.unrealengine.com/t/replicating-finstancedstruct-with-iris/1948348 "2026-10-30T11:18:54Z")
I know Iris is still experimental, but we wanted to give it a try. We got the warning (apart of many others like it) “LogIris: Warning: Generating descriptor for struct InstancedStruct that has custom serialization” bu… --- ## [\[Iris\] Struct replication lifetime condition ](https://forums.unrealengine.com/t/iris-struct-replication-lifetime-condition/2653599)
**Author:** [@anonymous-edc](https://forums.unrealengine.com/u/anonymous-edc)\ **Replies:** 4\ **Last updated:** [October 30, 2026, 11:16am UTC](https://forums.unrealengine.com/t/iris-struct-replication-lifetime-condition/2653599 "2026-10-30T11:16:15Z")
Hello, We’re working on implementing optimizations to bandwidth to reduce bandwidth and Iris TickClientConnections time and the most bandwidth cost comes from NPP’s sync and aux states. We’ve already switched NPP over t… --- ## [5.7 Iris Strategy ](https://forums.unrealengine.com/t/5-7-iris-strategy/2699685)
**Author:** [@anonymous-edc](https://forums.unrealengine.com/u/anonymous-edc)\ **Replies:** 4\ **Last updated:** [October 30, 2026, 11:05am UTC](https://forums.unrealengine.com/t/5-7-iris-strategy/2699685 "2026-10-30T11:05:16Z")
Hey folks, I wanted to ask a quick question about Iris in UE 5.7. Chiefly, what is the expectation for licensees when migrating from 5.6 to 5.7? For more context, we had some bugs when we enabled and tested Iris before… --- ## [Iris Replication with bNetLoadOnClient ](https://forums.unrealengine.com/t/iris-replication-with-bnetloadonclient/2704361)
**Author:** [@anonymous-edc](https://forums.unrealengine.com/u/anonymous-edc)\ **Replies:** 12\ **Last updated:** [October 30, 2026, 11:02am UTC](https://forums.unrealengine.com/t/iris-replication-with-bnetloadonclient/2704361 "2026-10-30T11:02:36Z")
Hi, We are in the process of converting our project to use Iris, but are having problems when bNetLoadOnClient is set. It would appear that when this is set, and the client spawns within relevancy range, the actor does… --- ## [Trying to enable Iris leads to crash: Assertion failed: ArraySerializer.IDCounter == 0 && ArraySerializer.ArrayReplicationKey == 0](https://forums.unrealengine.com/t/trying-to-enable-iris-leads-to-crash-assertion-failed-arrayserializer-idcounter-0-arrayserializer-arrayreplicationkey-0/2704931)
**Author:** [@JediKnightChan](https://forums.unrealengine.com/u/JediKnightChan)\ **Replies:** 2\ **Last updated:** [October 30, 2026, 10:59am UTC](https://forums.unrealengine.com/t/trying-to-enable-iris-leads-to-crash-assertion-failed-arrayserializer-idcounter-0-arrayserializer-arrayreplicationkey-0/2704931 "2026-10-30T10:59:48Z")
I tried to enable Iris in my game, which is originated from Lyra 5.1 template, I tried to do this both in 5.1 and in 5.2, where Iris is precompiled, but in both cases I got the following crash as soon as client tried to … --- ## [Jittery Character Movement on Client](https://forums.unrealengine.com/t/jittery-character-movement-on-client/1901237)
**Author:** [@Rainy\_Devil](https://forums.unrealengine.com/u/Rainy_Devil)\ **Replies:** 3\ **Last updated:** [October 29, 2026, 3:19am UTC](https://forums.unrealengine.com/t/jittery-character-movement-on-client/1901237 "2026-10-29T03:19:31Z")
Hi all, My team and I are working on a sport simulation project that runs in editor. Multiple characters are driven by data we receive and move around a field. Typically the operator will host on one machine, and anothe… --- ## [Some rules and things won't work ](https://forums.unrealengine.com/t/some-rules-and-things-wont-work/2845791)
**Author:** [@\_SA7](https://forums.unrealengine.com/u/_SA7)\ **Replies:** 0\ **Last updated:** [October 27, 2026, 4:59pm UTC](https://forums.unrealengine.com/t/some-rules-and-things-wont-work/2845791 "2026-10-27T16:59:00Z")
Title: Fortnite Creative Bug – Map Rules and Save Point Not Working for Players Who Join an Ongoing Session Sometimes, when my map is already running and players are playing, a new player joins the session and several t… --- ## [Apply Resimulation to Chaos Moudular Vehicle ](https://forums.unrealengine.com/t/apply-resimulation-to-chaos-moudular-vehicle/2694754)
**Author:** [@anonymous-edc](https://forums.unrealengine.com/u/anonymous-edc)\ **Replies:** 7\ **Last updated:** [October 27, 2026, 2:18pm UTC](https://forums.unrealengine.com/t/apply-resimulation-to-chaos-moudular-vehicle/2694754 "2026-10-27T14:18:04Z")
Hello Epic Games Support, I’m currently testing multiplayer using the Chaos Modular Vehicle system in Unreal Engine 5.5, and I’ve encountered an issue where the positions of vehicles between the server and client are no… --- ## [Network Prediction Plugin, Mover and Simulated Proxies not running SimulationTick](https://forums.unrealengine.com/t/network-prediction-plugin-mover-and-simulated-proxies-not-running-simulationtick/2658233)
**Author:** [@Neoptolemus](https://forums.unrealengine.com/u/Neoptolemus)\ **Replies:** 3\ **Last updated:** [October 27, 2026, 1:56pm UTC](https://forums.unrealengine.com/t/network-prediction-plugin-mover-and-simulated-proxies-not-running-simulationtick/2658233 "2026-10-27T13:56:10Z")
Hi all, I am working in 5.6 with the UMoverComponent for player movement. I noticed that even with the Simulated Proxy Network LOD setting on “Forward Predict”, simulated proxies never execute any code in the active mov… --- ## [In a multiplayer game the game mode OnLogout gets called during server travel, so how can I check if a player has actually left the game?](https://forums.unrealengine.com/t/in-a-multiplayer-game-the-game-mode-onlogout-gets-called-during-server-travel-so-how-can-i-check-if-a-player-has-actually-left-the-game/945043)
**Author:** [@rantrod](https://forums.unrealengine.com/u/rantrod)\ **Replies:** 3\ **Last updated:** [October 26, 2026, 6:36pm UTC](https://forums.unrealengine.com/t/in-a-multiplayer-game-the-game-mode-onlogout-gets-called-during-server-travel-so-how-can-i-check-if-a-player-has-actually-left-the-game/945043 "2026-10-26T18:36:08Z")
ue5.1 I’m keeping data on players I’d like to clear if they actually leave, but how to tell if they actually left or just server traveling? The destination map during server travel has a different game mode if that make… --- ## [Replicating object references?](https://forums.unrealengine.com/t/replicating-object-references/2233112)
**Author:** [@BiboDerTeppich](https://forums.unrealengine.com/u/BiboDerTeppich)\ **Replies:** 4\ **Last updated:** [October 21, 2026, 9:06pm UTC](https://forums.unrealengine.com/t/replicating-object-references/2233112 "2026-10-21T21:06:59Z")
I dont understand why object references refuse to replicate. It works fine with all other types of data/variables but not object refrences. --- ## [Previous Value of Replicated FFastArray empty ](https://forums.unrealengine.com/t/previous-value-of-replicated-ffastarray-empty/2720014)
**Author:** [@darkfire1321](https://forums.unrealengine.com/u/darkfire1321)\ **Replies:** 2\ **Last updated:** [October 21, 2026, 3:53pm UTC](https://forums.unrealengine.com/t/previous-value-of-replicated-ffastarray-empty/2720014 "2026-10-21T15:53:56Z")
Hello! I’ve been running into an odd bug with the previous value of the OnRep function parameter. I have a struct that inherits FFastArraySerializer that I have replicated to owners in an Actor Component. The actual rep… [Next page](https://forums.unrealengine.com/c/development-discussion/programming-scripting/multiplayer-networking/132.md?page=1)