I’m in the middle of a project right now and rigged a car with the Unreal Engine 4 Vehicle Rigging Addon for Blender and have followed the tutorials provided several times and everytime i try to import it to unreal 5.3 and 5.2 it crashes as soon as it appears in the content folder and autosaving out of date packages kicks in, and importing takes 15-20 minutes which seems like alot.
Export from blender was done on both blender 3.4 and 4.0
Imported with drag and drop, putting the fbx in the content folder and importing at startup, import into level and import to/game/projectname
the diagnostic after crash:
LoginId:8a5179504381612194e8fea93a2560a2
EpicAccountId:4bc34502802d4bb88e2feb712e295b3a
Assertion failed: !Ar.IsSaving() || (((int32) 0x80000000) <= Value && Value <= ((int32) 0x7fffffff)) [File:D:\build\++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\Serialization\BulkData.cpp] [Line: 129]
UnrealEditor_CoreUObject
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UnrealEditor_Engine
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UnrealEditor_Engine
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UnrealEditor_Engine
UnrealEditor_UnrealEd
UnrealEditor_UnrealEd
UnrealEditor_UnrealEd
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kernel32
ntdll
Use better blender plugins.
Epic’s trash has never worked. On top of being derivative / flat out unmaintained copies of other people’s work…
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thanks for your reply!
This plugin was recomended for me but i dont know what im doing wrong or what the diagnistic means.
Do you have another plugin for rigging a car for import to unreal from blender? Would make my life easier, or pehaps you know what the diagnistic means?
Youd have to download engine symbols - and you really should anyway - but its pointless for the problem at hand.
Your FBX export is probably bad/compromised or contains data it shouldn’t.
As far as plugins, etc.
There was one related to cars floating around the forum recently, but finding a specific needle in a haystack of similar needles is probably easier a task…
Base setup for vehicles (assuming no complex vehicle setups);
Armature + root bone.
Parented mesh - without wheels.
1 bone per wheel, parented to root - all pointed to the same side with the same bone rotation/axis.
Export to FBX even with the default blender plugin.
Import in engine, then set up wheels with a wheel mesh as you normally would.
Make sure your blender scene uses the correct Scale before you start working the armature setup.
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thanks once again for the reply, i will try all of them.
i dont know what you mean by engine symbols 
the plugin that was used creates an armature for the body and then rootbones for the wheels all facing the same direction but maybe i should try it without the plugin as you say!
digging deeper into the crash I turned to chatgtp and since im pretty much a beginner at unreal i found the crash log and it said
[0202/175851.758:ERROR:gpu_init.cc(426)] Passthrough is not supported, GL is disabled
i dont know why it says anithing about gl when im using directx 12 with the latest drivers installed and the project is set to directx12.
i will try your tips and see if i can get this rollercoaster going.
many thanks!
I learned that Chaos Vehicle requires the axis of the wheel bones to all point Z up and X forward, and exporting with GLB seemed to be the only way to get the axis orientation correct. You might try GLB instead of FBX. GLB is my preference moving forward for this reason alone.
1 Like
thanks for the commment!
i will try it right away!
thank you kindly for your time
Note that you could have fuzzed up your import setting axis for the FBX (or the export settings axis in blender).
There’s really no reason that the 2 pipeline would work any different…
No idea on why the fbx import would be attemting anything like this, but try the same import witout importong materials (the only thing that could potentially be at fault here).
Also do make sure your mesh has material slots if it needs to import.
This was fixed by the engine side importater at some point, to were even bad meshes without a material are just assigned a default instead of crashing… but ue5 could have seen a regression on this…
if you mean like this then i’ve tried it, i also removed some junk on the inside that will not be visible, ive joined all the bodies to one single unit except for wheels etc.
i got the same error when trying to import glb only withglb it didnt start the autosave right away and I could even place the car in the scene.
the crash occurs when the autosave kicks in or if i manually save.
i have one part of the mesh that does look quite white so im going to remove it to see if it lacks material.
I tried at an earlier stage to immport the car without the new wheels and without armature and was successful so my thoughts lean towards the armature causing problems.
at this moment im trying to rig the car without the addon as you suggested and hoping it works 
super big thanks for the support once again!
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If the import isn’t directly at fault for the crash, then something else that is used by the vehicle or maybe the wheels could be - particulalry if the crash happens after the items are added to the scene and the auto save (or a manual one) is attempted.
It could be just about anytning… look up what the engine Symbols are and how to install them, then the crash will give you some better details on what the core cause is…
if you mean add editor symbols im on it, tried before with another car and it still crashes so i dont think its the fbx file or glb file…
i will redo the crash with the editor symbols downloaded
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I read somewhere that the FBX export in Blender (or was it the import in UE5) was buggy and that GLB would solve the issue because it requires a single, specific axis orientation, so no implementation of exporter/importer could get it wrong by having to guess which axis orientation should be used and would be guaranteed compatible with the importer that reads the file.
All I can say is that I never had to do any export adjustments with GLB and it never gave me any issues.
No matter what I did with FBX, it wouldn’t get it right.
I couldn’t fix the issue with the GLB file, but I finally managed to solve it. I had no problem importing the FBX without the armature, but when the armature was included, it caused issues, and thats why I never reflected about polycount.
My model originally had around 9 million polys, and it seems Unreal couldn’t handle that with an armature attached, or perhaps it was too much for my PC. I attempted to remove unnecessary parts of the model, bringing it down to about 6 million faces, but that didn’t solve the problem.
However, last night I noticed that the rims alone were approximately 1.6 million polygons each. I found another pair on Sketchfab with only 120k faces, so I used them, and voila, it worked!
A big thanks for your involvement in trying to resolve my issue!
I managed to solve it!
it was a matter of polycounts that fixed it, see my other reply in the other comment
big thanks for your help, would’ve given up without it!
Ok so, there should be no limits to how many tris the engine imports but they need to be Tris.
In other words, you should always add a triangulation modifier and export your models with those applied when attempting to import into any engine.
Blender will be able to triangulate almost instanlty.
The engine will attempt to triangulate, but take loads of time to do so, and possibly crash (as experienced).
That said, even for a car manufaturer those numbers are rather extreem…
thanks for the tip, i will triangulate before export!
Yes it seemed quite extreme I agree but had no porblem importing the fbx by itself and halfed the polycount and still it still crashed so i started looking for other reasons
