Unreal Engine 5 Crashes when opening a level (due to nanite) - Help Needed!

Development Rendering
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Hey UEF,

Had a Unreal Engine 4 project that I upgraded issuelessly to UE-5 EA over a year ago - Just updated the UE-5 EA project to UE-5 Preview with everything working swell until I open a certain level or a older save of that level, in which the engine crashes.
The level(s) works fine on UE-5 EA, however has this issue with this latest update…

Using Windows 11, had the same issue on Windows 10 (doubt this means anything) - Hoping we can find a solution soon.

CallStack:

Assertion failed: ++Iterations < 256 [File:D:\build++UE5\Sync\Engine\Source\Developer\NaniteBuilder\Private\NaniteEncode.cpp] [Line: 962]

UnrealEditor_NaniteBuilder
UnrealEditor_NaniteBuilder
UnrealEditor_NaniteBuilder
UnrealEditor_NaniteBuilder
UnrealEditor_MeshBuilder
UnrealEditor_MeshBuilder
UnrealEditor_MeshBuilder
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
kernel32
ntdll

2 Likes
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The assertion fail is happening when iterating through your texture coordinate quantization. I would look at the offending levels in UE5.0EA and check if you might not have some complex objects with complex textures or involved material functions and then try turning Nanite off for those objects. Hope this helps get you on the right path.

1 Like
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Well it seems I’ve found a Solution -
After looking through nearly all my assets, I found 2 bugged assets that crashed the engine every time I opened/rendered them!
If someone else is having this issue, due the following to find and remove the assets:

I: Launch the engine

II: Open your content browser

III: typed in “static mesh” in the search bar (so all the listed assets are static meshes)

IV: Left Click the 1st asset, then while holding shift Left Click the last asset (so all the assets are highlighted)

V: Right Click one of the highlighted assets (it doesn’t matter which one, this should start loading them) - If everything is going right, this should crash the engine, giving you the same error!

VI: Relaunch the engine and follow steps (II & III) again.

VII: Instead of highlight all the assets and once, start highlight a row/a few at a time, right clicking and seeing if it crashes the engine

VIII: If everything goes to plan, you should short it down to one/a few assets causing the crash - Write down the assets name

IX: Close the engine and open your machine’s file manager

X: Find and Open your project’s files and go to the following: (“Drive’s name”:“Other Stuff may be here”“Your Project Name”\Content) - Open the content folder

XI: Search for the bugged assets name "that we wrote down at step (VIII)

XII: Drag it/them somewhere else (outside of the projects file)

XIII: Launch your engine again and launch your project

If you’re still having the issue, keep looking though all the static meshes as it’s likely more than one of them are causing the same problem (which was true in my case).

Hopefully this helped somebody and excuse my sloppy writing, it’s nearly 2 am for me… - uhdebbie

3 Likes
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Glad you found the issue!

5

Thank you. Was having this issue and it was driving me up the wall. Think I will ensure Build Nanite is unchecked when I import the mesh in the future.

6

having this issue with a custom map I created, was not having this issue in 5.1, but I could not build my project in 5.1 because of an engine bug, so I migrated to the UE 5.2, and now the engine crashes every time I try to load this map I have been working on for over 3 months. I just did the 5.2.1 update today, and was hoping that would fix it, but no…still crashes every time I try to load, will this issue be addressed by Epic anytime soon? Or should I just go back to the UE4 to avoid the constant crashing issues present in the Unreal Engine 5?

Update:
This solution worked for me, It was three static meshes, thankfully all in the same folder, I had to delete them from the project content folder, but it fixed the problem, thank you for the solution.

7

i got this problem with automotive bridge scene cuz i convert print to static mesh, then wen turning nanite it crash. i tried simplify material with only color parameter conected, still not work
failed: U >= 0 && U <= TexCoordMaxValueU [File:D:\build++UE5\Sync\Engine\Source\Developer\NaniteBuilder\Private\NaniteEncode.cpp] [Line: 1263]

8

I have the similar issue on 5.3.2 with OldWestLearning, the editor opens but crashes a few seconds later.

Fatal error!

Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0xffffffffffffffff

0x00007fff61a5d880 UnrealEditor-NaniteBuilder.dll!libmetis__CreateCoarseGraphNoMask() []
0x00007fff61a5f553 UnrealEditor-NaniteBuilder.dll!libmetis__Match_SHEM() []
0x00007fff61a5cc64 UnrealEditor-NaniteBuilder.dll!libmetis__CoarsenGraph() []
0x00007fff61a5447b UnrealEditor-NaniteBuilder.dll!libmetis__MultilevelBisect() []
0x00007fff61a541ca UnrealEditor-NaniteBuilder.dll!libmetis__MlevelRecursiveBisection() []
0x00007fff61a5400b UnrealEditor-NaniteBuilder.dll!METIS_PartGraphRecursive() []
0x00007fff61a266b2 UnrealEditor-NaniteBuilder.dll!FGraphPartitioner::BisectGraph() [D:\build\++UE5\Sync\Engine\Source\Developer\NaniteBuilder\Private\GraphPartitioner.cpp:181]
0x00007fff61a027c8 UnrealEditor-NaniteBuilder.dll!`FGraphPartitioner::PartitionStrict'::`8'::<lambda_1>::operator()<TYCombinator<`FGraphPartitioner::PartitionStrict'::`8'::<lambda_1> > >() [D:\build\++UE5\Sync\Engine\Source\Developer\NaniteBuilder\Private\GraphPartitioner.cpp:305]
0x00007fff61a0286e UnrealEditor-NaniteBuilder.dll!`FGraphPartitioner::PartitionStrict'::`8'::<lambda_1>::operator()<TYCombinator<`FGraphPartitioner::PartitionStrict'::`8'::<lambda_1> > >() [D:\build\++UE5\Sync\Engine\Source\Developer\NaniteBuilder\Private\GraphPartitioner.cpp:321]
0x00007fff61a0286e UnrealEditor-NaniteBuilder.dll!`FGraphPartitioner::PartitionStrict'::`8'::<lambda_1>::operator()<TYCombinator<`FGraphPartitioner::PartitionStrict'::`8'::<lambda_1> > >() [D:\build\++UE5\Sync\Engine\Source\Developer\NaniteBuilder\Private\GraphPartitioner.cpp:321]
0x00007fff61a33239 UnrealEditor-NaniteBuilder.dll!UE::Core::Private::Function::TFunctionRefCaller<TYCombinator<`FGraphPartitioner::PartitionStrict'::`8'::<lambda_1> >,void __cdecl(FGraphPartitioner::FGraphData *)>::Call() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Templates\Function.h:480]
0x00007fff61a1f560 UnrealEditor-NaniteBuilder.dll!`TLocalWorkQueue<FGraphPartitioner::FGraphData>::AddWorkers'::`18'::<lambda_1>::operator()() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Async\LocalWorkQueue.h:119]
0x00007fff61a33634 UnrealEditor-NaniteBuilder.dll!LowLevelTasks::TTaskDelegate<LowLevelTasks::FTask * __cdecl(bool),48>::TTaskDelegateImpl<`LowLevelTasks::FTask::Init<`TLocalWorkQueue<FGraphPartitioner::FGraphData>::AddWorkers'::`18'::<lambda_1> >'::`11'::<lambda_1>,0>::CallAndMove() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Async\Fundamental\TaskDelegate.h:171]
0x00007fff888a8cd5 UnrealEditor-Core.dll!LowLevelTasks::FTask::ExecuteTask() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Async\Fundamental\Task.h:627]
0x00007fff888a8bbc UnrealEditor-Core.dll!LowLevelTasks::FScheduler::ExecuteTask() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Private\Async\Fundamental\Scheduler.cpp:172]
0x00007fff888880e2 UnrealEditor-Core.dll!LowLevelTasks::FScheduler::TryExecuteTaskFrom<LowLevelTasks::TLocalQueueRegistry<1024>::TLocalQueue,&LowLevelTasks::TLocalQueueRegistry<1024>::TLocalQueue::DequeueGlobal,0>() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Private\Async\Fundamental\Scheduler.cpp:350]
0x00007fff888d08c2 UnrealEditor-Core.dll!LowLevelTasks::FScheduler::WorkerMain() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Private\Async\Fundamental\Scheduler.cpp:378]
0x00007fff88898b60 UnrealEditor-Core.dll!UE::Core::Private::Function::TFunctionRefCaller<`LowLevelTasks::FScheduler::CreateWorker'::`2'::<lambda_1>,void __cdecl(void)>::Call() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Templates\Function.h:480]
0x00007fff88a7f773 UnrealEditor-Core.dll!FThreadImpl::Run() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Private\HAL\Thread.cpp:69]
0x00007fff88eb4e32 UnrealEditor-Core.dll!FRunnableThreadWin::Run() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Private\Windows\WindowsRunnableThread.cpp:149]
0x00007fff88ea8667 UnrealEditor-Core.dll!FRunnableThreadWin::GuardedRun() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Private\Windows\WindowsRunnableThread.cpp:79]
0x00007ff89a91257d KERNEL32.DLL!UnknownFunction []

Crash in runnable thread Background Worker #12
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I’m not sure if you’ve already solved this, but if not please check here to see if this solution will work: