Lightmass Crash when building the level

Development Rendering
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1

I just started playing around with the latest 4.71 update and already I have a problem.
After I updated the engine, I opened it and just tried a build with the standard template level to see if everything is ok. - It is not.
The first run, I got a bluescreen.
After rebooting I tried again, this time (and in all the attempts that followed) I got this error message at the begin of the build and no build is performed.

For all non-german speakers, the message says : The procedure entry point “??1FString@@QEAA@XZ” could not be found in DLL “UnrealLighmass-Core.dll”

31929-builderror.jpg
31929-builderror.jpg1142×634 38 KB

What is the problem now??
Any help is appreciated :slight_smile:

Cheers,
Klaus

2

Hi Klaus,

On my system here I’m not able to see this same issue.

Is this a source build or binary? Can you verify that there isn’t a second swarm agent opened in the task bar?

I know you mentioned this was broken after rebooting from the BSoD with 4.7, what about any other versions of the editor?

If this is the Launcher version can you go to the Launcher > Library > Select Engine Version > Drop Down > Click Verify. If anything is broken it should try and resolve this. If this doesn’t work possibly uninstalling and re-installing 4.7.1 may resolve the issue.

Let me know.

3

Hi Tim,

Thanks for the suggestions :slight_smile:
The build was via launcher. The last good known version for me was 4.71 preview 2.
I ran all other preview updates to stay on top of things but could not test them, thus I dont know if they would have worked.

I verified the installation in the launcher. Nothing suspicious there.
I removed the engine and redownloaded/insatlled it again.

Now Im getting the following error:

---------8<–snip----------------------------------------------------------------------------------------------------------------

Error === Lightmass crashed: ===
Assertion failed: Importer.ImportData((FBaseMaterialData*)this) [File:D:\BuildFarm\buildmachine_++depot+UE4-Releases+4.7\Engine\Source\Programs\UnrealLightmass\Private\ImportExport\Material.cpp] [Line: 14]

KERNELBASE.dll!UnknownFunction (0x000007fefdaa940d) + 0 bytes [UnknownFile:0]
UnrealLightmass-Core.dll!UnknownFunction (0x000007feccaa44f4) + 0 bytes [UnknownFile:0]
UnrealLightmass-Core.dll!UnknownFunction (0x000007fecc982878) + 0 bytes [UnknownFile:0]
UnrealLightmass-Core.dll!UnknownFunction (0x000007fecc961075) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!Lightmass::FMaterial::Import() (0x000000013f7bbddc) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!Lightmass::FLightmassImporter::ConditionalImportObject > >() (0x000000013f7594e0) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!Lightmass::FStaticLightingMesh::Import() (0x000000013f7be1e4) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!Lightmass::FStaticMeshStaticLightingMesh::Import() (0x000000013f820a1a) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!Lightmass::FLightmassImporter::ImportObjectArray > >() (0x000000013f76060b) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!Lightmass::FScene::Import() (0x000000013f7bd1b4) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!Lightmass::FLightmassImporter::ImportScene() (0x000000013f7be6ef) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!Lightmass::BuildStaticLighting() (0x000000013f78e81e) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!Lightmass::LightmassMain() (0x000000013f7c4f72) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!main() (0x000000013f7e1950) + 0 bytes [UnknownFile:0]
UnrealLightmass.exe!__tmainCRTStartup() (0x000000013f836467) + 0 bytes [UnknownFile:0]
kernel32.dll!UnknownFunction (0x00000000779959ed) + 0 bytes [UnknownFile:0]
ntdll.dll!UnknownFunction (0x0000000077bcc541) + 0 bytes [UnknownFile:0]
ntdll.dll!UnknownFunction (0x0000000077bcc541) + 0 bytes [UnknownFile:0]

---------8<–snip----------------------------------------------------------------------------------------------------------------

Needless to say that hex-address technobabble completely elludes me :wink:

Cheers,
Klaus

4

Okay, since we’ve got to this point where Lightmass is at least working again. Can you try deleting the derived data cache (X: / Users / [Your Computer Name] / AppData / Local / UnrealEngine / ). Remove everything in this folder is fine.

Also, open Swarm Agent (Taskbar) > Menu > Cache > click Clean and then Validate.

I’ve not been able to see a different in compile and build times for lightmass between 4.6 and 4.7 that I’m aware of. This is here on our beefy machines or at home on my mid-range machine.

Let me know if this helps.

5

Hi,

I tried your approach and had some success with it.
Since the issue was also occuring in other levels and projects after they initially worked, I could narrow it down to the following:

It seems that the SM_Brush asset (the shrub thinggy) from the starter content is causing this. I always get the error message once I add it to the level. If I remove it, Lightmass builds without any complaint…

I usually work with own assets and rarely play around with the starter content, so I never noticed this ind of issues…

Is there perhaps something corrupt with this asset?

Cheers,
Klaus

6

There could possibly be something that became corrupted with the mesh. In my tests though I never had an issue with it. I just did a test in the FPS template with some of the starter content and ~20 of these bush meshes with no issue.

If you’re able to build lighting without it crashing that’s the more important part.