Check the permission of your installation dir and all its parent dirs and maybe you’ll find something
Permissions are fine, managed to fix the Launcher.dat to get rid of that but still same error, tried moving the directory to be in a base E:\UE_5.8 in case it was path name related and even installed it on an entirely separate PC, different Epic account, entirely different setup and tried the patch over there, same issue. It just says my InstalledBuild.txt doesn’t contain the text it contains and the xxh patch says the directory still doesn’t exist
Edit: On the second PC, while the installer does not work at all, the other command to check the hash DOES work now, reporting this as an error
C:\Patching> ./hdiffz “-M-check#Base.xxh128” “C:\UE_5.8”
inputDir : “C:\UE_5.8”
inManifest : “Base.xxh128”
check manifest found an error: checksum_manifest file: C:\UE_5.8\Engine\Plugins\Experimental\GPULightmass\Source\GPULightmassEditor\Private\GPULightmassEditorModule.cpp ERROR!
Notice it’s looking for GPULightmassEditorModule.cpp, all I’ve got there is GPULightmassEditorModule.h, so we need Editor Source installed, and that fixed the patcher. Is the source actually used for this patching or did you just run it against your own install folder that included the source and that ended up in the hash list? Because I don’t recall needing Editor Source installed in the only previous versions drag and drop 7z install method.
The launcher does not have an Editor Source option and GPULightmassEditorModule.cpp is always installed, so your installed version is somehow weird
Edit: maybe you don’t have Engine Source installed?
Sent DM with project.
Meant Engine Source, not Editor, whoops. And GPULightmassEditorModule.cpp didn’t exist until I turned Engine Source on in my Install options, at which point your installer worked as expected. Figured it’s just worth a noting here for anyone else in the future if they, like me, don’t normally install Engine Source since they don’t use it. Since your installer fails without it.
The proper size of Engine Source is around ~593MiB (reported by the launcher) so it doesn’t really take much space but your launcher is reporting some really large value which is also strange.
Release 5.8.0 2026.07.28
https://downloads.luoshuangfw.io/gpulm-releases/GPULM-5.8.0.exe
Back to release list
- Add support for direct (static lights only) and indirect lighting contrast (spherical harmonics smoothing) and intensity control
- There is also a per-light override for direct lighting contrast (static lights only)
Since the first version of GPULM, a stupid bug has caused direct lighting from static lights to be twice as intense as intended. It is now fixed.
Some technical detail:
Direct Lighting Contrast is mainly for removing negative values from the sphere, so 0 means the minimal value over the sphere is guaranteed to be >= 0.
Indirect Lighting Contrast is more like an artist control: 0 means removing all directionality and you’ll get the average value over the sphere.
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Seeming to get a GPU crash as of the latest hotfix for 5.8 - 5.8.1. I tried the recent patch after fresh installing (verifying engine files) and got a version mismatch warning saying the injector failed at the end of the install so I am assuming that is why as I believe your last update was just before it if I am reading the time right. I don’t know if this already on your radar, but just letting you know.
Thanks for all that you do to continue supporting GPU Lightmass @yujiang.wang .
Cheers.
Yes it was just before patch hence missmatch.
Release 5.8.1 2026.07.30
https://downloads.luoshuangfw.io/gpulm-releases/GPULM-5.8.1.exe
Back to release list
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hi, trying the new update for 581. While installing this error occurs. Did a verify from launcher but didn’t help. Any suggestions?
I’ve updated the installer and you can try again.
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Hey, quick question, do the binary releases work properly with debug symbols or am I gonna have to do my own engine build? I’d prefer to know before I spend a bunch of time doing an engine build if I don’t need to!
The binary installer does not contain debug symbols as they are going to make the installer huge.
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alright, cool, good to know.