URDF importer extension causing segfault when running update() on imported scene

[julakshah]

Hi Isaac Sim team,
I'm facing an issue with - I believe - the urdf importer. Thank you for any help!

Description

I've created a custom urdf of my robot and am trying to import it and run the corresponding scene headless through a python script. According to my log, the import and opening is successful but when the script hits the SimulationApp.update() step it crashes from a segfault. I'm fairly certain it is due to the urdf importer because when I open a dummy usd scene I don't get a segfault and I removed everything else that I think could be causing the issue. I've attached a simplified script that I run that causes the issue.

Now, thinking that the segfault might be due to my own urdf's configuration, I copied the cater robot urdf and meshes directly from the github and tried importing them in the same way. This also causes the crash.

I'm still pretty new to isaac, so I may be overlooking something simple, but I would love some suggestions on what I'm doing wrong and whether others are able to reproduce the issue.

Steps to reproduce

I've created a repo with the steps to reproduce in the readme: https://github.com/julakshah/isaac_urdf_importer_minimal

Isaac Sim version

• 6.0.1

nvidia-smi Output (from crash log)

|---------------------------------------------------------------------------------------------|
| Driver Version: 580.173.02    | Graphics API: Vulkan
|=============================================================================================|
| GPU | Name                             | Active | LDA | GPU Memory | Vendor-ID | LUID       |
|     |                                  |        |     |            | Device-ID | UUID       |
|     |                                  |        |     |            | Bus-ID    |            |
|---------------------------------------------------------------------------------------------|
| 0   | NVIDIA RTX 1000 Ada Generation.. | Yes: 0 |     | 6141    MB | 10de      | 0          |
|     |                                  |        |     |            | 28b9      | fdb4959e.. |
|     |                                  |        |     |            | 1         |            |
|---------------------------------------------------------------------------------------------|
| 1   | Intel(R) Arc(tm) Graphics (MTL)  |        |     | 23656   MB | 8086      | 0          |
|     |                                  |        |     |            | 7d55      | 8680557d.. |
|     |                                  |        |     |            | 0         |            |
|=============================================================================================|
| OS: 22.04.5 LTS (Jammy Jellyfish) ubuntu, Version: 22.04.5, Kernel: 6.8.0-134-generic
| XServer Vendor: The X.Org Foundation, XServer Version: 12101004 (1.21.1.4)
| Processor: Intel(R) Core(TM) Ultra 7 155H
| Bare Metal Cores: 16 | Bare Metal Logical Cores: 32
| Available Cores:  22 
|---------------------------------------------------------------------------------------------|
| Total Memory (MB): 31542 | Free Memory: 25485
| Total Page/Swap (MB): 2047 | Free Page/Swap: 2047
|---------------------------------------------------------------------------------------------|

Logs

logs can be found in the logs/ directory in the linked repo.

Additional Information

• I understand my laptop is well below the minimum requirements for isaacsim but from all of my tests I don't believe this issue is related to a lack of ram
• Laptop uses IOMMU to manage the two gpus. As far as I can tell this isn't causing the issue because isaac automatically disregards the intel graphics card on boot

2026-07-27T23:10:58Z [1,463ms] [Warning] [omni.rtx] Skipping unsupported non-NVIDIA GPU: Intel(R) Arc(tm) Graphics (MTL)
2026-07-27T23:10:58Z [1,464ms] [Warning] [omni.rtx] Skipping unsupported non-NVIDIA GPU: Intel(R) Arc(tm) Graphics (MTL)

• I am able to boot native isaacsim normally without issue
  • I am able to use the gui to open the imported urdf->usda (from script) and run without isaac crashing despite the same file creating a crash in the script.
• When writing the urdf importer configuration I referenced the docs/dosctrings in the isaacsim repo here

Please let me know if anything else is needed to help diagnose. Thank you.

[vick-yu]

Thanks for the detailed report and the repro repo -- the logs point to a hardware
compatibility issue as the root cause.

Root Cause: GPU Below Minimum Spec

Your GPU (NVIDIA RTX 1000 Ada, 6 GB VRAM) does not meet the minimum requirements
for Isaac Sim 6.0.1. Per the
official system requirements:

	Minimum
GPU	GeForce RTX 4080
VRAM	16 GB

The docs note explicitly:

"Due to VRAM constraints, some tutorials and benchmarks may not run on GPU
below the minimum specifications. Workflows leveraging a large number of
sensors are particularly affected."

The crash itself occurs during the first simulation_app.update() call, when
the RTX renderer attempts to compile Vulkan shaders for the scene geometry.
This is a memory-intensive step that the RTX 1000 Ada (6 GB VRAM, IOMMU enabled,
and only 2 GB swap) cannot sustain.

Workaround

Switching to headless=True in your SimulationApp config reduces GPU memory
pressure significantly by bypassing the full RTX renderer and skipping shader
compilation overhead. Note that headless=True is actually the default -- your
script explicitly overrides it:

simulation_app = SimulationApp({
    "headless": True,
    # rest of your config...
})

This may allow simpler workflows to run, but results are not guaranteed on
unsupported hardware. For anything beyond basic testing, a GPU meeting the
minimum spec (RTX 4080 / 16 GB VRAM) is required.

Additional Notes

• The URDF importer itself is not the cause -- your logs confirm the import and
  stage open both complete successfully before the crash.
• The built-in Carter URDF at
  {isaac_sim_root}/exts/isaacsim.asset.importer.urdf/data/urdf/robots/carter/urdf/carter.urdf
  can be used for testing without cloning the external repo.

[julakshah]

Hello, thank you for taking the time to respond.

I can see that the gpu requirements are not met but contrary to that, I am able to open and run the generated scene fine through the gui, and it doesn't come close to using all of the ram. The only time I've had it crash is when it gets opened a run directly through a python script. I ran the following scene fine as shown through the gui but tried running it through the script and I get the same crash as before.