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UE5.1 VR Projects Crash on Play with OpenXR + Vive Cosmos Elite

Kyle G

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Question: Has anyone successfully launched a “VR Preview” or "Standalone Game" of a Unreal Engine 5.1.1 VR project using a Vive Cosmos Elite and the OpenXR plugin? Mine crashes on every play.

Steps to Reproduce: Create a fresh copy of the UE5.1 VR template with Starter Content. Ensure that the "OpenXR" and "Vive Wave OpenXR - Windows" plugins are enabled. Play default level in VR using "VR Preview" or "Standalone Game" with SteamVR app and VIVE Console app running. Crashes every time.

Error Message Reported: Assertion failed: InOutSizeX != 0 && InOutSizeY != 0 [File:D:\build\++UE5\Sync\Engine\Plugins\Runtime\OpenXR\Source\OpenXRHMD\Private\OpenXRHMD.cpp] [Line: 890] Full Crash Logs: For the full Unreal VR Template crash logs follow this link.

Attempted Fixes: Things I’ve tried, based on other unreal forum posts:

  • Switched targeted RHI from DX12 to DX11 or Vulcan in Project Settings => Platforms => Windows => Default RHI. Result: Same crash as above.

  • Switched VR plugin from OpenXR to SteamVR plugin. Result: VR Preview works when using SteamVR plugin, but controller buttons don’t function. (Likely because the deprecated StreamVR plugin doesn’t support the Enhanced Input System used by the template project.)

  • I have also attempted to launch the ViveOpenXRGame UE5.1 Sample Project found here, specifically the ControllerInputMap. Result: Also crashes, occasionally with the same assertion error, but often with a series of XR_ERROR_HANDLE_INVALID errors. Full Crash Logs: For the full ViveOpenXRGame crash logs follow this link.

Help Please: I'd appreciate any suggestions on how to fix or further debug this issue. I've got 18 game dev students up here in Winnipeg, Manitoba, Canada hoping to learn about crafting VR experiences using Vive gear and Unreal Engine.

Devices and Software Versions:
Unreal Version: 5.1.1
VR Device: Vive Comos Elite (All firmware up to date.)
OpenXR Plugin: 1.0
Vive Wave OpenXR - Windows Plugin (OpenXR PC VR Plugin): 1.6.0
Steam VR Version: 1.25.7
VIVE Console Version:
GPU: Nvidia GeForce RTX 3080 (Driver version 531.41)
OS: Windows 11 (22H2 22621.1413)


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I've been struggling with this for over a week now.  Reading all the docs and scouring every forum and Discord and Reddit channel I can find for any information.  We are not the only one's having this issues.

Good luck getting a response from HTC.  People complain about the Unreal docs, but I think they are amazing compared to HTC.

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I think I've found the solution thanks to one of the Epic staff over at their forums.

The Solution For @Dan Lauer And Others Who Might Have This Problem: If you cannot launch Epic’s UE5.1 Default VR Template with a Vive Cosmos Elite using the OpenXR Plugin:

  1. Ensure that along with Epic’s OpenXR plugin, that your project also includes the latest Vive OpenXR plugin in your project’s Plugins folder.
  2. Ensure that you’ve enabled the developer settings in the SteamVR app and have changed your OpenXR runtime from ViveOpenXR to SteamVR: Instructions here.


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