Frequent but Intermittent crashes on IOS devices, 5.5.4

Development Platform & Builds Mobile
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1

Log from device

Working on getting proper stacktrace, but does not crash when plugged into xcode : (

EDIT : Seems to be PSO related

PSOPrecompilePool #0 (36)

`Mar 31 10:59:06 Helsinki-iPad-8 mygame(Metal)[1024] : Compiler failed to build request
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:214][ 0]LogMetal: Error: Failed to generate a pipeline state object: Error Domain=AGXMetalA12 Code=3 “Vertex attribute 1 is not defined in the vertex descriptor.” UserInfo={NSLocalizedDescription=Vertex attribute 1 is not defined in the vertex descriptor.}
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:215][ 0]LogMetal: Error: Failed to generate a pipeline state object: Error Domain=AGXMetalA12 Code=3 “Vertex attribute 1 is not defined in the vertex descriptor.” UserInfo={NSLocalizedDescription=Vertex attribute 1 is not defined in the vertex descriptor.}
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:215][ 0]LogMetal: Error: Vertex shader: Hash: C87407B8D66CA0C226C15BA7A5DDA67B982AF9A4, Name: Main_000051a2_bc96e682
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:215][ 0]LogMetal: Error: Vertex shader: Hash: C87407B8D66CA0C226C15BA7A5DDA67B982AF9A4, Name: Main_000051a2_bc96e682
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:215][ 0]LogMetal: Error: Pixel shader: Hash: C65E33A460785EBB4ACEC09A35F5E8B6A08494B3, Name: Main_00000f2c_d30f1a2b
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:215][ 0]LogMetal: Error: Pixel shader: Hash: 7712C53ED0576C4AF3C9FCBAF4F8D155BCCE0DFF, Name: Main_00000acf_dd585923
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:215][ 0]LogMetal: Error: Descriptor: <MTLRenderPipelineDescriptorInternal: 0x1102edb00>
label = Main_000051a2_bc96e682+Main_00000acf_dd585923
Alpha to Coverage = 0
Alpha to One = 0
Rasterization Enabled = 1
Sample Coverage = 1
Sample Mask = 0xffffffffffffffff
Raster Sample Count = 1
Input Primitive Topology = Unspecified
Depth Attachment Format = MTLPixelFormatDepth32Float_Stencil8
Stencil Attachment Format = MTLPixelFormatDepth32Float_Stencil8
tessellationPartitionMode = MTLTessellationPartitionModePow2
maxTessellationFactor = 16
tessellationFactorScaleEnabled = 0
tessellationFactorFormat = MTLTessellationFactorFormatHalf
tessellationControlPointIndexType = MTLTessellationControlPointIndexTypeNone
tessellationFactorStepFunction = MTLTessellationFactorStepFunctionConstant
tessellationOutputWindingOrder = MTLWindingClockwise
Vertex Function = <_MTLFunctionInternal: 0x1103b6f40>
na<\M-b\M^@\M-&>

Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:230][ 0]LogMetal: Error: Failed to generate a pipeline state object: Error Domain=AGXMetalA12 Code=3 “Vertex attribute 1 is not defined in the vertex descriptor.” UserInfo={NSLocalizedDescription=Vertex attribute 1 is not defined in the vertex descriptor.}
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:230][ 0]LogRHI: Error: Failed to create graphics pipeline, hashes: Vertex: AFD02BB90176577DBBC5020C8E1006C4FCF3AAC5, Pixel: E116234464E23B9CC3658140DE32190B7FC8E823, Pipeline: 8182847825D10EDE53F3958C4C62074077C18EC3.
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:230][ 0]LogRHI: Error: Failed to create graphics pipeline, hashes: Vertex: AFD02BB90176577DBBC5020C8E1006C4FCF3AAC5, Pixel: A49D18AE77F2EAFC12171C44451C827502CAACB1, Pipeline: DE4EAA4CF64E5AB3AADBD005BCB71047D7F36738.
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:230][ 0]LogRHI: Error: Failed to create graphics pipeline, hashes: Vertex: D93F838DC6702949CFFD6233F8E3470913657AD6, Pixel: 8AF7B0C5BB713A8ADFDACF81A7B1358AC461D60A, Pipeline: 6831360D88409ECBF1E8DA7E39173CBF705229FD.
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:230][ 0]LogMetal: Error: Vertex shader: Hash: D93F838DC6702949CFFD6233F8E3470913657AD6, Name: Main_0000219e_94a648e1
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:230][ 0]LogRHI: Error: Vertex: Main_00005108_78dcc486
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:230][ 0]LogRHI: Error: Pixel: Main_00002c85_10053d79
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:230][ 0]LogRHI: Error: Render Targets: (8)
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:230][ 0]LogRHI: Error: 0x1a
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:230][ 0]LogRHI: Error: 0x15
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:230][ 0]LogRHI: Error: 0x0
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:230][ 0]LogRHI: Error: 0x0
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:230][ 0]LogRHI: Error: 0x0
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:230][ 0]LogRHI: Error: 0x0
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:230][ 0]LogRHI: Error: 0x0
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:230][ 0]LogRHI: Error: 0x0
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:230][ 0]LogRHI: Error: Depth Stencil Format:
Mar 31 10:59:06 Helsinki-iPad-8 mygame[1024] : [UE] [2025.03.31-07.59.06:231][ 0]LogRHI: Error: 0xb`

2

Steps to Reproduce
Observations:

  • Crash is intermittent. Sometimes on entering the game, sometimes not
  • A near-blank test project does _not_ crash

Things we have tried so far:

  • Using Metal v3.0

Things we have yet to try:

  • Using deferred rendering ( trying that now )

Crash Log below

3

Hi Tuomas,

Thank you for the report and log. Can you confirm that you are on 5.5.3 or higher? We are tracking the issue and believe this may have been introduced after 5.5.2.

Best regards.

4

Hi Peter and Tuomas.

We were able to confirm the issue in the 5.5 release, however, it appears to be resolved in the main development branch. We will try to track down a fix CL and get back to you.

Best regards.

5

Hi Tuomas,

We believe the following changelists should provide resolution to this issue:

https://github.com/EpicGames/UnrealEngine/commit/c2f5dcbeb2936ff7fd2b9af8e2f3f6322505ce80

https://github.com/EpicGames/UnrealEngine/commit/330de5ad0c5f3712a2141905b1aa1e6a88f93951

Best regards.

6

Correct, 5.5.4

Can also confirm r.PSOPrecaching=0 restores stability

7

Hi Stephane!

I stumbled on this thread since we had a similar issue on PC with a gpu crash dump describing an MMU Fault Error. It’s from a shipping build so we can’t extract much information of it.

The game is running on 5.5.4 as well. Is there a bug tracking link for this issue or some code we can downgrade to before this bug got introduced?

Thanks!

8

Super, thank you