UE5.3.1 crashes on start up using dx12 ever since 'build all levels' [Solved]

[AmaiTrick]

I’m still pretty new to Unreal Engine so hopefully I can get some help. Did a lot of digging and nothing seems to be helping my particular situation.

I attempted to ‘Build All Levels’ and UE5 crashed when I did this. Since then it would crash on starting up that project (I can open other projects just fine). I learned I can switch to dx11 and load the project up fine, but dx12 is consistently crashing.

I read that third person projects can cause this, however this was a ‘blank’ project not the ‘third person’ preset.

This is the error code I get:

Assertion failed: !HasAnyFlags(RF_NeedPostLoad) [File:D:\build++UE5\Sync\Engine\Source\Runtime\Engine\Private\Materials\MaterialInstance.cpp] [Line: 2444]

UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_Landscape
UnrealEditor_Landscape
UnrealEditor_Landscape
UnrealEditor_CoreUObject
UnrealEditor_CoreUObject
UnrealEditor_CoreUObject
UnrealEditor_Engine
UnrealEditor_Engine
UnrealEditor_CoreUObject
UnrealEditor_Engine
UnrealEditor_CoreUObject
UnrealEditor_CoreUObject
UnrealEditor_CoreUObject
UnrealEditor_CoreUObject
UnrealEditor_CoreUObject
UnrealEditor_CoreUObject
UnrealEditor_UnrealEd
UnrealEditor_UnrealEd
UnrealEditor_UnrealEd
UnrealEditor_Core
UnrealEditor_Engine
UnrealEditor_UnrealEd
UnrealEditor_UnrealEd
UnrealEditor_UnrealEd
UnrealEditor_UnrealEd
UnrealEditor_UnrealEd
UnrealEditor
UnrealEditor
UnrealEditor
UnrealEditor
UnrealEditor
kernel32
ntdll

[AmaiTrick]

Okay this was driving me absolutely nuts so I was going over every single setting I had changed since the last time I had built anything which was… quite a while back.

I finally figured it out.

Apparently enabling nanite does not like to work, it was what caused it to crash. So I’m leaving this here for people who might have the same issue; try disabling nanite if you have it enabled.