UE 5.4.2: Landscape Grass Crash

Development World Creation
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1

I was trying to migrate a map created in UE 5.1.1 to UE 5.4.2. I migrated it successfully, but when I open it and move around in it, the editor closes with the error:

Assertion failed: CellIndex < CellIndexMax [File:D:\build++UE5\Sync\Engine\Source\Runtime\Renderer\Private\SceneCulling\SceneCulling.h] [Line: 172]

I managed to isolate the problem to the LandscapeGrassOutput. To check if it was a migration issue, I created a new project and followed this steps:

1- Create a new UE 5.4.2 project
2- Create a new level. Add lights.
3- Create a new Landscape (scale it to 3000 in x and y, since it happens at large distances)
4- Create a new material and apply it to the landscape
5- Add a LandscapeGrassOutput node
6- Create a Landscape Grass, apply it to the node and place a scalar with value 1
7- Place a cube as Grass Mesh, with density = 1. Everything else at default values.

Captura
Captura628Ă—539 28.9 KB

8- Check that it works.
9- Increase the “Start Culling Distance” value to the maximum.
10- Increase the “End Culling Distance” value to the maximum. (I didn’t test it to see what the minimum value is, but it’s higher than 500000)
11- If the crash hasn’t happened yet, move the camera at high speed through the level.
12- The Editor closes.
13- The Crash Reporter appears with the following
Assertion failed: CellIndex < CellIndexMax [File:D:\build++UE5\Sync\Engine\Source\Runtime\Renderer\Private\SceneCulling\SceneCulling.h] [Line: 172]

The last lines of the log:

[2024.06.11-15.03.27:907][721]LogWindows: Error: appError called: Assertion failed: CellIndex < CellIndexMax [File:D:\build++UE5\Sync\Engine\Source\Runtime\Renderer\Private\SceneCulling\SceneCulling.h] [Line: 172]

[2024.06.11-15.03.27:907][721]LogWindows: Windows GetLastError: La operaciĂłn se completĂł correctamente. (0)
[2024.06.11-15.03.39:331][721]LogAudioMixer: Warning: AudioMixerPlatformInterface Timeout [11 Seconds] waiting for h/w. InstanceID=1
[2024.06.11-15.03.39:332][721]LogWindows: Error: === Critical error: ===
[2024.06.11-15.03.39:332][721]LogWindows: Error:
[2024.06.11-15.03.39:332][721]LogWindows: Error: Assertion failed: CellIndex < CellIndexMax [File:D:\build++UE5\Sync\Engine\Source\Runtime\Renderer\Private\SceneCulling\SceneCulling.h] [Line: 172]
[2024.06.11-15.03.39:332][721]LogWindows: Error:
[2024.06.11-15.03.39:332][721]LogWindows: Error:
[2024.06.11-15.03.39:332][721]LogWindows: Error:
[2024.06.11-15.03.39:332][721]LogWindows: Error: [Callstack] 0x00007ffca8bfecd0 UnrealEditor-Renderer.dll!UnknownFunction
[2024.06.11-15.03.39:332][721]LogWindows: Error: [Callstack] 0x00007ffca8c487d1 UnrealEditor-Renderer.dll!UnknownFunction
[2024.06.11-15.03.39:332][721]LogWindows: Error: [Callstack] 0x00007ffca8bee848 UnrealEditor-Renderer.dll!UnknownFunction
[2024.06.11-15.03.39:332][721]LogWindows: Error: [Callstack] 0x00007ffca8bce963 UnrealEditor-Renderer.dll!UnknownFunction
[2024.06.11-15.03.39:332][721]LogWindows: Error: [Callstack] 0x00007ffca8c38194 UnrealEditor-Renderer.dll!UnknownFunction
[2024.06.11-15.03.39:332][721]LogWindows: Error: [Callstack] 0x00007ffca8baac7e UnrealEditor-Renderer.dll!UnknownFunction
[2024.06.11-15.03.39:332][721]LogWindows: Error: [Callstack] 0x00007ffca8baecdd UnrealEditor-Renderer.dll!UnknownFunction
[2024.06.11-15.03.39:332][721]LogWindows: Error: [Callstack] 0x00007ffcb457ac8d UnrealEditor-Engine.dll!UnknownFunction
[2024.06.11-15.03.39:332][721]LogWindows: Error: [Callstack] 0x00007ffcb7dc6be0 UnrealEditor-RenderCore.dll!UnknownFunction
[2024.06.11-15.03.39:332][721]LogWindows: Error: [Callstack] 0x00007ffcb7e03175 UnrealEditor-RenderCore.dll!UnknownFunction
[2024.06.11-15.03.39:332][721]LogWindows: Error: [Callstack] 0x00007ffcb81ab88a UnrealEditor-Core.dll!UnknownFunction
[2024.06.11-15.03.39:332][721]LogWindows: Error: [Callstack] 0x00007ffcb81abf2e UnrealEditor-Core.dll!UnknownFunction
[2024.06.11-15.03.39:332][721]LogWindows: Error: [Callstack] 0x00007ffcb7e3181f UnrealEditor-RenderCore.dll!UnknownFunction
[2024.06.11-15.03.39:332][721]LogWindows: Error: [Callstack] 0x00007ffcb7e364c4 UnrealEditor-RenderCore.dll!UnknownFunction
[2024.06.11-15.03.39:332][721]LogWindows: Error: [Callstack] 0x00007ffcb87ec93d UnrealEditor-Core.dll!UnknownFunction
[2024.06.11-15.03.39:332][721]LogWindows: Error: [Callstack] 0x00007ffcb87e02b7 UnrealEditor-Core.dll!UnknownFunction
[2024.06.11-15.03.39:332][721]LogWindows: Error: [Callstack] 0x00007ffd1df17344 KERNEL32.DLL!UnknownFunction
[2024.06.11-15.03.39:332][721]LogWindows: Error:

I hope someone can guide me to solve this problem, since I cannot continue working until I solve it.

3

Probably access the unreal repo and review the code for that page at that line to get an idea.

My guess is they incorrectly hard coded a max value so that you cannot set it to anything other than default.

It normally takes them a month or so to release fixes, so you may want to consider pulling the code of the latest build - fixing it yourself - and using the custom built engine going forward without updating it futher (or you just catch more bugs).

4

I have the exact same problem with the same version, were you able to solve it somehow?

5

I had the same issue, I guess the grass node isn’t work fine in 5.4 because i tried to see if i did something wrong in 5.3, but works fine, so the problem is just in 5.4 (that’s why I’m seeking for this specific topic and found this thread)