Niagara Skeletal Mesh CPU Access Error in 4.26

[MerriemWeebster]

I recently moved my 4.25 project to 4.26, and my niagara systems are no longer working because of the Skeletal Mesh Location module. The mesh has CPU Access enabled, the result in preview is different from what it is shown in playtime.

The emitter

The mesh with CPU access enabled (material has opacity set to 0 by default and the arrow is just a preview attachment)

Emitter runs fine when put in the editor

How it looks when I enter play mode, similar results when running a standalone game

What the logs say, this issue persists for all skeletal meshes and every new emitter I make and even for new skeletal meshes that I import, CPU is unable to access the skeletal mesh regardless of what I do

The logs:

LogNiagara: Skeletal Mesh Data Interface is trying to use triangle sampling function 'RandomTriangle', but either no CPU access is set on the mesh or the data is invalid. Interface: NiagaraDataInterfaceSkeletalMesh /Game/Particles/BowSpawnNiagaraEmitter1_System.BowSpawnNiagaraEmitter1_System:BowSpawnNiagaraEmitter1.SpawnScript_90.NiagaraDataInterfaceSkeletalMesh_1
LogNiagara: Skeletal Mesh Data Interface is trying to use triangle sampling function 'GetSkinnedTriangleDataWSInterpolated', but either no CPU access is set on the mesh or the data is invalid. Interface: NiagaraDataInterfaceSkeletalMesh /Game/Particles/BowSpawnNiagaraEmitter1_System.BowSpawnNiagaraEmitter1_System:BowSpawnNiagaraEmitter1.SpawnScript_90.NiagaraDataInterfaceSkeletalMesh_1
LogNiagara: Skeletal Mesh Data Interface is trying to use triangle sampling function 'RandomTriangle', but either no CPU access is set on the mesh or the data is invalid. Interface: NiagaraDataInterfaceSkeletalMesh /Game/Particles/BowNiagaraEmitter_System.BowNiagaraEmitter_System:BowNiagaraEmitter.SpawnScript_0.NiagaraDataInterfaceSkeletaMesh_0
LogNiagara: Skeletal Mesh Data Interface is trying to use triangle sampling function 'GetSkinnedTriangleDataWSInterpolated', but either no CPU access is set on the mesh or the data is invalid. Interface: NiagaraDataInterfaceSkeletalMesh /Game/Particles/BowNiagaraEmitter_System.BowNiagaraEmitter_System:BowNiagaraEmitter.SpawnScript_0.NiagaraDataInterfaceSkeletalMesh_0

[imorb]

Do we have some solutions on this? Anyone?

[MerriemWeebster]

You’re the first person the respond after an entire year, lmao

[MerriemWeebster]

I still haven’t found a solution btw, even after the latest update to the engine…

[MerriemWeebster]

I pretty much gave up on trying to figure out the reason behind the error, hope you’re able to find something on your end.

[mystyphy_dev]

I have reproduced this issue with a marketplace project file. Trying to debug now.

[mystyphy_dev]

For MW and anyone that comes across this, I resolved a similar issue with marketplace content doing a Full Rebuild on each Niagara system (It’s an option under the Compile arrow in the system). This works for most of the systems. Two systems would not rebuild and caused UE4 to hang indefinitely.

To resolve this, I built the 4.26.1 build from GitHub source and used it. Everything worked in that build. Not sure why the launcher build behaves differently.

[anonymous_user_0d5d0b83]

Hello,

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Thanks

[namrog84]

I was running into this error in UE5.1 Lyra project.
The bug didn’t happen on the regular SK_Mannequin (Manny or Quinn).

In the warning itself it’s saying “either no CPU access is set on the mesh or the data is invalid”

So I checked my new mesh (in my case a frog skeleton mesh) I had needed to enable “Allow CPUAccess” under the LOD Info.

After checkboxing this. It started to work just fine. and no more Niagara warnings