UE 5.5.4 Linux Vulkan Crashes During UMG ComboBoxString Interactions – VK_ERROR_DEVICE_LOST / RHI Resource Deletion

General Issues and Bug Reporting (Unreal Engine)
1

Summary

Unreal Engine 5.5.4 crashes intermittently on Linux (Vulkan) during repeated UMG ComboBoxString dropdown interactions. Logs show VK_ERROR_DEVICE_LOST during swapchain recreation and a separate RHI “Resource is being deleted” assertion. Disabling PSO precaching did not resolve the issue.

What Type of Bug are you experiencing?

Platform Other

Steps to Reproduce

  1. Launch a packaged Unreal Engine 5.5.4 Development build on Linux using Vulkan SM6.
  2. Open a UMG interface containing Unreal Engine’s built-in ComboBoxString dropdown widgets.
  3. Repeatedly open and close the dropdowns, switching between different selections.
  4. Continue interacting with the UI for several minutes.
  5. The application intermittently crashes with VK_ERROR_DEVICE_LOST or an RHI resource-deletion assertion.

Note: The crash is intermittent and not consistently reproducible. Logs show repeated Vulkan swapchain creation and Slate window destruction before the device-lost error.

The issue persists with PSO precaching disabled.

Expected Result

The application should remain stable when repeatedly opening, closing, and changing selections in UMG ComboBoxString dropdown widgets. Vulkan swapchain creation and destruction should be handled correctly without causing VK_ERROR_DEVICE_LOST, RHI resource-deletion assertions, or application crashes.

Observed Result

The application intermittently crashes during repeated UMG ComboBoxString dropdown interactions.

The Vulkan log shows repeated swapchain creation and Slate window destruction, followed by:

LogVulkanRHI: Error: Result failed, VkResult=-4
at Runtime/VulkanRHI/Private/VulkanMemory.cpp:4703
with error VK_ERROR_DEVICE_LOST

A separate crash also produces the following RHI assertion:

Assertion failed: (OldPacked & DeletingBit) == 0
File: Runtime/RHI/Public/RHIResources.h
Line: 136
Resource is being deleted.

Both errors terminate the application. The crashes are intermittent, and disabling PSO precaching has not resolved the issue.

Affects Versions

5.5

Platform(s)

Linux
Windows

For crash reports, include your callstack

Crash 1 — RHI Resource Deletion Assertion

Assertion failed: (OldPacked & DeletingBit) == 0
File: Runtime/RHI/Public/RHIResources.h
Line: 136

Resource is being deleted.

Unhandled Exception: SIGSEGV
Invalid attempt to write memory at address 0x0000000000000003

Callstack:

FVulkanPipelineStateCacheManager::RHICreateGraphicsPipelineState(FGraphicsPipelineStateInitializer const&)
FVulkanDynamicRHI::RHICreateGraphicsPipelineState(FGraphicsPipelineStateInitializer const&)
FCompilePipelineStateTask::CompilePSO(FGraphicsPipelineStateInitializer::EPSOPrecacheCompileType const*)
TGraphTask<FCompilePipelineStateTask>::ExecuteTask()
UE::Tasks::Private::FTaskBase::TryExecuteTask()
LowLevelTasks::FScheduler::ExecuteTask()
LowLevelTasks::FScheduler::WorkerLoop()
LowLevelTasks::FScheduler::WorkerMain()
FThreadImpl::Run()
FRunnableThreadPThread::Run()
FRunnableThreadPThread::_ThreadProc()

Crash 2 — Vulkan Device Lost

LogVulkanRHI: Error: Result failed, VkResult=-4
at Runtime/VulkanRHI/Private/VulkanMemory.cpp:4703
with error VK_ERROR_DEVICE_LOST

LogCore: FUnixPlatformMisc::RequestExit(1, VerifyVulkanResult)

The second crash log does not contain a symbolized callstack; it records a Vulkan device-lost error followed by a request to terminate the application.

Both errors have occurred during testing on Unreal Engine 5.5.4 Linux Development builds with Vulkan SM6.

Additional Notes

We are experiencing intermittent Vulkan crashes in Unreal Engine 5.5.4 packaged Development builds on Linux.

System Configuration:

  • OS: CentOS Stream 9 (Kernel 5.14.0-352.el9.x86_64)
  • GPU: NVIDIA RTX A4000
  • NVIDIA Driver: 595.99.02
  • Rendering API: Vulkan SM6
  • Window System: X11 (SDL2)

Additional Findings:

  • The crashes appear to occur more frequently during repeated UMG ComboBoxString interactions, particularly when opening and closing dropdowns rapidly.
  • Logs show repeated Vulkan swapchain creation and Slate window destruction immediately before the VK_ERROR_DEVICE_LOST failure.
  • We have also encountered a separate RHI resource-deletion assertion during asynchronous Vulkan pipeline-state compilation.
  • Disabling PSO precaching did not eliminate the crashes. We confirmed the following settings were applied:
r.PSOPrecaching=0
r.PSOPrecache.Components=0
r.PSOPrecache.Resources=0
r.PSOPrecache.GlobalShaders=0
  • Despite these settings, Vulkan initialization reports Vulkan PSO Precaching = 1, PipelineFileCache = 0.

Questions for Epic:

Is this a known Vulkan/Slate resource-lifetime or swapchain synchronization issue in UE 5.5.4?

Have related issues been addressed in Unreal Engine 5.8.4?

Are there recommended workarounds or additional debugging options for identifying the underlying cause?

We can provide additional sanitized logs or diagnostic information if required.