Crash in Vulkan Pipeline Cache with Meta XR Plugin on UE 5.5.3 (Plugin Version 72.0.1)

[DCDBionicman]

We are experiencing a crash on mobile VR devices when running our project with Unreal Engine 5.5.3 and Meta XR Plugin version 72.0.1. The crash occurs during Vulkan initialization—in particular, within the function FVulkanCombinedChunkCacheFile::UpdateMapping, which results in a null pointer dereference. Notably, this issue did not occur with Unreal Engine 5.4 using the same Meta XR plugin.

Environment:

• Unreal Engine: 5.5.3
  

• Meta XR Plugin: Version 72.0.1
  

• Platform: Android (tested on Oculus devices)
  

• Rendering API: Vulkan
  

Steps to Reproduce:

1. Create or update a project to use Unreal Engine 5.5.3 with the Meta XR Plugin (v72.0.1).
   

2. Configure the project to build for Android with Vulkan.
   

3. Deploy the application to a VR device.
   

4. Launch the application.
   

5. The application initially displays the preview but then crashes immediately.
   

What We’ve Tried:

Disabling Vulkan Pipeline Cache:
We added the following lines to our DefaultEngine.ini:

[SystemSettings]
r.Vulkan.EnablePipelineCache=0
r.Vulkan.OfflinePipelineCache=0
r.Vulkan.ChunkedPipelineCache=0

This did not resolve the crash.

Disabling Mobile Multi‑View and Instanced Stereo:
We set the Android runtime settings in DefaultEngine.ini as follows:

[/Script/AndroidRuntimeSettings.AndroidRuntimeSettings]
bMultiView=false
bMultiViewInstancedStereo=false

However, the issue persists.

Clearing Vulkan Cache Files:
We also attempted deleting any cached Vulkan pipeline files (e.g., from Saved/VulkanPipelineCache), but the crash remains.

Crash Log Excerpt:

signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x0
Backtrace:
  #00 pc 0x1237cfec  /.../libUnreal.so (FVulkanCombinedChunkCacheFile::UpdateMapping(unsigned int)+104)
  #01 pc 0x1237ca78  /.../libUnreal.so (FVulkanCombinedChunkCacheFile::ReadAllCacheChunks(...)+896)
  #02 pc 0x1237aac4  /.../libUnreal.so (FVulkanCombinedChunkCacheFile::LoadAllCacheChunks(...)+400)
  ...

Additional Notes:

This issue appears to be related to changes in the Vulkan pipeline cache system introduced in UE 5.5.x.
The crash does not occur when using UE 5.4, which indicates a regression or compatibility issue with the newer engine version in combination with the Meta XR Plugin.

Request:
Could you please investigate this regression? Any guidance on a workaround or an upcoming fix would be greatly appreciated.

[DCDBionicman]

Log of the issue (closed by mistake)

PTSamples.log