Iris Replication - [5.8.2] - Seamless travel - Client initialization RPCs dropped during seamless travel due to a client/server race

Development Programming & Scripting Multiplayer & Networking
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We’re hitting the same issue described in [[Iris] Seamless travel not working in [Content removed] HandleSeamlessTravelPlayer sends client initialization RPCs before the replacement PlayerController has been registered with the Iris replication system. We tried the suggested workaround of deferring HandleSeamlessTravelPlayer until UWorld::OnWorldBeginPlay, but it doesn’t fully resolve the problem for us. Our current workaround splits HandleSeamlessTravelPlayer into two phases: the controller swap runs immediately, and initialization is deferred until the world has begun play. But, this leaves the controller in a half-initialized state during UWorld::BeginPlay(), which has its own side effects.

Is there a recommended approach from Epic, or any update on the timeline for https://issues.unrealengine.com/issue/UE-354365?

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Steps to Reproduce
Similar repro steps to those described in UE-354365

  • In a project using Iris, enable seamless travel on the game mode.
  • Have a server and client initiate a seamless travel, ensuring the client finishes the travel before the server. (This can be done by running the server and client in different processes, allowing you to hit a break point during travel on only the server process.)
  • Observe the “SendRPC” warnings in the log for functions such as ClientGotoState, ClientSetHUD, ClientEnableNetworkVoice, ClientRestart, etc.
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Hi,

Thank you for the report. With other development tasks taking priority, there unfortunately haven’t been any updates on UE-354365, and I can’t provide any estimate as to when a fix may be available.

Given that we haven’t been able to fully test any solutions or workarounds, we don’t have a single recommended approach. Another option could be to swap and fully initialize the player controller immediately, and then only defer the actual RPC calls until after the world has begun play. Again though, there may be side effects to this as well.

Thanks,

Alex

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Thanks for the information Alex

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