5.5 baked lightmaps error

Development Rendering
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1

When building lighting on a converted 5.4 project to 5.5 i get

LightingResults: Error: Import Volumetric Lightmap failed: Expected 64 tasks, only 0 were reported as completed from Swarm

No other errors are listed. Same project static lighting builds fine in 5.4.4

7900xtx
7950x
64gb ram

Tested with an empty Level with a single stationary light and singe static mesh as well with same result

Even get the message on a completely empty level

I figure it must be a bug as the baked lighting worked great in 5.4.4

1 Like
2

further looking into the logs:

[2024.12.23-22.44.32:515][856]LogStaticLightingSystem: Warning: No importance volume found, so the scene bounding box was used.  You can optimize your scene's quality and lighting build times by adding importance volumes.
[2024.12.23-22.44.32:515][856]LogStaticLightingSystem: Running Lightmass w/ ImmediateImport mode ENABLED
[2024.12.23-22.44.32:515][856]LogStaticLightingSystem: Running Lightmass w/ ImmediateProcess mode ENABLED
[2024.12.23-22.44.32:515][856]LogStaticLightingSystem: Running Lightmass w/ Sorting mode ENABLED
[2024.12.23-22.44.32:515][856]LogStaticLightingSystem: Running Lightmass w/ Mapping paddings ENABLED
[2024.12.23-22.44.32:515][856]LogStaticLightingSystem: Running Lightmass w/ Mapping debug paddings DISABLED
[2024.12.23-22.44.32:533][856]LogEditorBuildUtils: Build time 0:00
[2024.12.23-22.44.32:623][858]LogUObjectHash: Compacting FUObjectHashTables data took   0.40ms
Failed to find game directory: /home/blackbeard/unreal/UnrealLightmass/Binaries
Assertion failed: Tag == ETaskTag::EGameThread [File:./Runtime/Core/Private/HAL/ThreadingBase.cpp] [Line: 88] 
The Gamethread can only be tagged on the inital thread of the application
appError called: Assertion failed: Tag == ETaskTag::EGameThread [File:./Runtime/Core/Private/HAL/ThreadingBase.cpp] [Line: 88] 
The Gamethread can only be tagged on the inital thread of the application

Signal 11 caught.
Malloc Size=262146 LargeMemoryPoolOffset=262162 
Malloc Size=262146 LargeMemoryPoolOffset=524338 

=== Lightmass crashed (Signal=11): ===
1001[2024.12.23-22.44.32:855][862]LightingResults: Error: Import Volumetric Lightmap failed: Expected 64 tasks, only 0 were reported as completed from Swarm
[2024.12.23-22.44.33:108][862]LogUObjectHash: Compacting FUObjectHashTables data took   0.23ms
[2024.12.23-22.44.33:143][862]LogStaticLightingSystem: Illumination: 575.677 ms (6 us encoding lightmaps, 6 us encoding shadowmaps)
[2024.12.23-22.44.33:143][862]LogStaticLightingSystem: Lightmap texture memory:  0.0 MB (0.0 MB streaming, 0.0 MB non-streaming), 0 textures
[2024.12.23-22.44.33:143][862]LogStaticLightingSystem: Shadowmap texture memory: 0.0 MB (0.0 MB streaming, 0.0 MB non-streaming), 0 textures
[2024.12.23-22.44.33:143][862]DumpUnbuiltLightIteractions
[2024.12.23-22.44.33:143][862]Lights with unbuilt interactions: 0
[2024.12.23-22.44.33:143][862]
[2024.12.23-22.44.33:143][862]Primitives with unbuilt interactions: 0
[2024.12.23-22.44.33:175][862]Cmd: MAP CHECK NOTIFYRESULTS
[2024.12.23-22.44.33:175][862]MapCheck: Map check complete: 0 Error(s), 0 Warning(s), took 0.118ms to complete.
[2024.12.23-22.44.34:587][934]LogSlate: Window 'Message Log' being destroyed
[2024.12.23-22.44.34:628][934]LogSlate: Window 'Message Log' being destroyed

this is the 5.5.1 from https://www.unrealengine.com/en-US/linux

When i switch back to 5.4.4 i no longer get the crash or the Failed to find game directory: /home/blackbeard/unreal/UnrealLightmass/Binaries

Looks like the Assertion around the gamethread is causing the UnrealLightmass crash

3

Attempted to file an issue at https://unrealbugsubmissions.epicgames.com but the captcha keeps saying invalid

4

@theblackbeard420 Just here to say I got the same error and my log says pretty much the same thing as yours and thus I cannot build lighting on Linux. I also obtained my Unreal 5.5.1 from https://www.unrealengine.com/en-US/linux though I upgraded my project from 5.3.

Have not yet found a solution.

A newly created project also fails to build lighting. The lighting build works fine on Windows, though.

5

Still got the error on 5.5.2 on linux unfortunately.

I did send a bug report to Epic with a link to this thread for further details, hopefully this gets resolved, while I know Linux isn’t a priority this has been a bug since 5.5.0 and didn’t exist on 5.4 and 5.3 but i’m unable to use either 5.3 or 5.4 due to the high amount of crashes, i’m stuck on 5.5.