After reproducing the issue, the crash will happen very likely occur because the new parent doesn’t have a layer.
Another annoying issue, not sure if it could be considered a bug or is by design, when I toggle off a layer from a material that has multiple parents made from it, the change does not propagate to its children, so once you create an instance of a layered material, you cannot depend on the toggle visibility button.
Steps to Reproduce
To reproduce the issue, find the material instances called MI_Material_To_Reparent and MI_Causes_Crash.
If you change the parent of MI_Material_To_Reparent, from MI_Opaque_Weather to MI_Causes_Crash, the moment you check the layer tab, the engine will crash.
Hello [mention removed],
I attempted to reproduce the issue using the launcher version of UE 5.6 following the steps you described. I changed the parent material of MI_Material_To_Reparent from MI_Opaque_Weather to MI_Causes_Crash but was not able to trigger a crash when opening the Layer Parameters tab.
Could you confirm whether you’re using a source build or the launcher build? Also, if possible, could you share a callstack or log from the crash?
Please let me know.
Best,
Francisco
It happens in any case. The test I made was from the launcher, and it should happen in cases I think, the number of layers that it had before is smaller than the number on the new ones.
Assertion failed: EditorOnly.LayerStates.IsValidIndex(Index) [File:D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Public\Materials\MaterialLayersFunctions.h] [Line: 591]
Hello [mention removed],
Thanks for the reply. I attempted to reproduce the crash by reparenting MI_Material_To_Reparent to a MI with fewer layers but I wasn’t able to trigger the issue on my end.
Could you please share a simplified repro project where the crash occurs consistently? If possible, a full callstack file or crash log would also be very helpful.
Best,
Francisco
Hello [mention removed],
I’ve made a JIRA report to be added to the Unreal issue tracker website. You will be able to track the resolution by checking this link: Unreal Engine Issues and Bug Tracker (UE\-308768)
Please note that Epic ultimately determines whether the issue will be made publicly accessible and the process may take a few days. The tracking link might not work immediately.
I’ll close the case now but feel free to reply if you have anything else to add.
Best,
Francisco
By using the same project I uploaded, pen the MI_Material_To_Reparent, on the detail tab, change the parent from the MI_Opaque_Weather to MI_Causes_Crash, select Layer Parameters Tab, at least in my machine is a 100% crash rate[Image Removed]
Hello [mention removed],
Thanks, I was able to reproduce the crash now. I noticed that saving the asset and closing the window before selecting the Layer Parameters tab seems to prevent the crash. Once reopened, the asset no longer crashes when focusing on that tab.
That said, this is not expected and very likely an engine bug. I’ll dig into this further and follow up soon.
Best,
Francisco