Description

The Swarm binaries are missing from Engine\Binaries\DotNET in the 5.7 Preview launcher version of the engine. This causes any lighting build or precomputed static visibility builds to fails due to the missing binaries. Functionality can be restored by copying the Swarm binaries from a previous version of the engine. This issue has been confirmed on: 5.7.0-45973471+++UE5+Release-5.7. The following binaries appear to be missing:
SwarmAgent.exe
SwarmCoordinator.exe
SwarmCoordinatorInterface.dll
SwarmInterface.dll

Steps to Reproduce
  • Launch the Launcher 5.7 Preview (5.7.0-45973471+++UE5+Release-5.7) Engine.
  • Create a VRTemplate project (already setup for static lighting)
  • Click Build -> Build Lighting Only
  • Observe that Swarm fails to launch with the following error: Failed to initialize Swarm. Check to make sure you have the right version of Swarm installed.
Callstack

LogOutputDevice: Error: === Handled ensure: ===
LogOutputDevice: Error: Ensure condition failed: false [Link Removed] [Line: 568]
LogOutputDevice: Error: Error initializing Swarm interface.
LogOutputDevice: Error: Stack:
LogOutputDevice: Error: [Callstack] 0x00007ff84ff6817b UnrealEditor-SwarmInterface.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff84ff642c4 UnrealEditor-SwarmInterface.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff84ff64373 UnrealEditor-SwarmInterface.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff8346baa69 UnrealEditor-UnrealEd.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff834696afa UnrealEditor-UnrealEd.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff8346bb9f3 UnrealEditor-UnrealEd.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff834696f5e UnrealEditor-UnrealEd.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff833d1395c UnrealEditor-UnrealEd.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff82e5e27e5 UnrealEditor-LevelEditor.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff82e608e17 UnrealEditor-LevelEditor.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff8358d26f5 UnrealEditor-Slate.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff8358d287e UnrealEditor-Slate.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff8359d0297 UnrealEditor-Slate.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff8359d3fe0 UnrealEditor-Slate.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff8359ae77a UnrealEditor-Slate.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff835a2774b UnrealEditor-Slate.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff835a40756 UnrealEditor-Slate.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff8359d57d9 UnrealEditor-Slate.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff83581fc79 UnrealEditor-Slate.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff835868e59 UnrealEditor-Slate.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff83585ba4a UnrealEditor-Slate.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff8358530d9 UnrealEditor-Slate.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff891d3e7a7 UnrealEditor-ApplicationCore.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff891d2669a UnrealEditor-ApplicationCore.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff891d41386 UnrealEditor-ApplicationCore.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff891d1ffa1 UnrealEditor-ApplicationCore.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff96c787846 USER32.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff96c78539d USER32.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff891d63e89 UnrealEditor-ApplicationCore.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff6d0794af9 UnrealEditor.exe!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff6d07b0c3e UnrealEditor.exe!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff6d07b0d4a UnrealEditor.exe!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff6d07b45d0 UnrealEditor.exe!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff6d07c5c04 UnrealEditor.exe!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff6d07c8fba UnrealEditor.exe!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff96d26e8d7 KERNEL32.DLL!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff96deec53c ntdll.dll!UnknownFunction []

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Fixed
Fix Commit47277153
CreatedOct 23, 2025
ResolvedOct 23, 2025
UpdatedOct 23, 2025
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