When i tried to import an obj file into UE5 it immediatly crashes with this:
Assertion failed: IsInGameThread() [File:D:\build++UE5\Sync\Engine\Plugins\Interchange\Runtime\Source\Import\Private\Material\InterchangeMaterialFactory.cpp] [Line: 417]
UnrealEditor_InterchangeImport
UnrealEditor_InterchangeEngine
UnrealEditor_InterchangeEngine
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
kernel32
ntdll
3 Likes
Are you building UE from source? Which commit are you on?
Can you share the obj and associated material files + textures with me? We need to make sure this is fixed.
In the meantime you can deactivate “Interchange pipeline” support for OBJ to default back to “legacy” import
Use this CVAR Interchange.FeatureFlags.Import.OBJ False
2 Likes
Hi, I’m having the exact same issue with 5.1. It doesnt matter which OBJ file I try to import, UE5.1 crashes everytime. I’ve been trying to find the “interchange pipeline” setting in the project settings but I can’t find anything that matches your description. Also, I’m fairly new to UE so I don’t know how to use the provided CVAR, maybe someone could walk me through that.
Thanks in advance 
1 Like
Hey all,
Getting the same exact issue on my end. Importing the OBJ without Creating Materials seems to work temporarily, but the engine crashes after a couple of minutes on my end. Seems to affect all projects and happens with any OBJ file. Have also tried reinstalling Unreal Engine 5.1.
Here are some of the things I’ve done that cause the crashes to become less frequent:
-
Changing the CVAR variable that @UE_FlavienP recommended (refer to document, once plugin is downloaded, search for “import.obj” and you should find " Interchange.FeatureFlags.Import.OBJ" and click on where it says True to set it to false).
-
Another process that made crashes less frequent was entering NVIDIA Control Panel (Search via Windows Start Menu), Then go to Manage 3D settings → Global Settings and Click Restore.
Crashes are still quite frequent but I hope this helps y’all and hopefully we can find a solution together.
1 Like
Can I get a sample. I cannot reproduce the crash on 5.1
Also had the same issue with .obj file. Thank you, CVAR helped and now legacy FBX import shows up when I try import .obj model. Also would be nice to set it up as a parameter in project settings.
Thank you!
I would also like to add on this Interchange Pipeline Import:
- This importer ignores absolutely all material slots of the model. I export model from Blender and choose “write materials”. Legacy FBX Import - sees all this parameters and imports model Correctly.
Here how it works with Legacy FBX Import (correct way) :
- Interchange Pipeline Import also ignores axis of the model. (I set it up Z up, Y forward for Chaos Vehicle as stated in UE documentation.) After imoport Axis are twisted in unnatural way and model flipped in wrong direction.
I hope these issues would be addressed. I am willing to share any data with you so you can try it yourself.
All the best!
Interchange FBX was incomplete this is why it was deactivated in 5.1.
Will check with the dev. If you can send me a sample FBX in private message that would be good.
Thank you.
Hey guys,
When I started having this issue I noticed that even if I didn’t import an obj, many other interactions with the engine would result in a crash, which would lead to me crashing in the first 10 seconds of starting the engine, or a couple of minutes later. I have not tried importing an obj yet but this seems to help fix the crashes (at least for the time being.)
Go to Project Settings
Search Default RHI
Switch from DirextX 12 to DirectX 11.
Hope this helps.
Same crush. cant find solution
1 Like
Was having this same issue (with files I have used on other versions on older projects) . This worked for me.
