[Bug]: Windows Desktop crashes on AMD RX 6900 XT during torch.cuda.is_available() with PyTorch ROCm 2.9.1+rocm7.2.1

[massimomazzariol]

App Version

ComfyUI Desktop version: not sure / not available from the current logs.

Environment details from startup log:

• OS: Windows 11
• GPU: AMD Radeon RX 6900 XT
• AMD driver version: 32.0.21043.12001
• Python version: 3.12.12
• Python executable: C:\Users\Max\AppData\Local\Comfy-Desktop\ComfyUI-Installs\ComfyUI\ComfyUI.venv\Scripts\python.exe
• ComfyUI path: C:\Users\Max\AppData\Local\Comfy-Desktop\ComfyUI-Installs\ComfyUI\ComfyUI
• PyTorch version: 2.9.1+rocm7.2.1
• torch.version.hip: 7.2.53211-158bd99533
• torch.version.cuda: None

Expected Behavior

ComfyUI Desktop should either:

1. Start correctly using the AMD ROCm/HIP backend on the AMD Radeon RX 6900 XT, or
2. Detect that this AMD/RDNA2 setup is unsupported and fail gracefully with a clear error message instead of crashing with a native Windows access violation.

Direct PyTorch verification should also return a normal result. In particular:

python -c "import torch; print(torch.cuda.is_available())"

should return either True or False, not crash or exit without printing a value

Actual Behavior

ComfyUI Desktop crashes during startup before the UI becomes usable.

The crash happens during GPU/backend detection, around:

torch.cuda.is_available()

The startup log reports:

Windows fatal exception: access violation

Direct verification inside the ComfyUI Desktop virtual environment also behaves incorrectly:

• torch is installed as ROCm/HIP:
  2.9.1+rocm7.2.1
• torch.version.hip returns:
  7.2.53211-158bd99533
• torch.version.cuda returns:
  None

However:

python -c "import torch; print(torch.cuda.is_available())"

does not print True or False. It only prints:

[WARNING] failed to run offload-arch: binary not found.

and then returns to the prompt.

Also:

python -m torch.utils.collect_env

starts collecting environment information but does not complete with the expected environment report

Steps to Reproduce

1. Install ComfyUI Desktop on Windows 11
2. Let the installer create the AMD/ROCm environment
3. Start ComfyUI Desktop
4. ComfyUI Desktop starts the security scan
5. After ComfyUI-Manager pre-startup, the process crashes
6. The terminal shows a Windows fatal exception: access violation

Debug Logs

[START] Security scan
[DONE] Security scan
** ComfyUI startup time: 2026-06-21 20:50:13.695
** Platform: Windows
** Python version: 3.12.12 (main, Feb 12 2026, 00:40:26) [MSC v.1944 64 bit (AMD64)]
** Python executable: C:\Users\Max\AppData\Local\Comfy-Desktop\ComfyUI-Installs\ComfyUI\ComfyUI\.venv\Scripts\python.exe
** ComfyUI Path: C:\Users\Max\AppData\Local\Comfy-Desktop\ComfyUI-Installs\ComfyUI\ComfyUI
** ComfyUI Base Folder Path: C:\Users\Max\AppData\Local\Comfy-Desktop\ComfyUI-Installs\ComfyUI\ComfyUI
** User directory: C:\Users\Max\AppData\Local\Comfy-Desktop\ComfyUI-Installs\ComfyUI\ComfyUI\user
** ComfyUI-Manager config path: C:\Users\Max\AppData\Local\Comfy-Desktop\ComfyUI-Installs\ComfyUI\ComfyUI\user\__manager\config.ini
** Log path: C:\Users\Max\AppData\Local\Comfy-Desktop\ComfyUI-Installs\ComfyUI\ComfyUI\user\comfyui.log
[INFO] [PRE] ComfyUI-Manager
[WARNING] failed to run offload-arch: binary not found.
Windows fatal exception: access violation

Stack (most recent call first):
  File "C:\Users\Max\AppData\Local\Comfy-Desktop\ComfyUI-Installs\ComfyUI\ComfyUI\.venv\Lib\site-packages\torch\cuda\__init__.py", line 182 in is_available
  File "C:\Users\Max\AppData\Local\Comfy-Desktop\ComfyUI-Installs\ComfyUI\ComfyUI\.venv\Lib\site-packages\comfy_kitchen\backends\cuda\__init__.py", line 1138 in _register
  File "C:\Users\Max\AppData\Local\Comfy-Desktop\ComfyUI-Installs\ComfyUI\ComfyUI\.venv\Lib\site-packages\comfy_kitchen\backends\cuda\__init__.py", line 1149 in <module>
  File "C:\Users\Max\AppData\Local\Comfy-Desktop\ComfyUI-Installs\ComfyUI\ComfyUI\.venv\Lib\site-packages\comfy_kitchen\__init__.py", line 3 in <module>
  File "C:\Users\Max\AppData\Local\Comfy-Desktop\ComfyUI-Installs\ComfyUI\ComfyUI\comfy\quant_ops.py", line 7 in <module>
  File "C:\Users\Max\AppData\Local\Comfy-Desktop\ComfyUI-Installs\ComfyUI\ComfyUI\comfy\memory_management.py", line 8 in <module>
  File "C:\Users\Max\AppData\Local\Comfy-Desktop\ComfyUI-Installs\ComfyUI\ComfyUI\comfy\utils.py", line 25 in <module>
  File "C:\Users\Max\AppData\Local\Comfy-Desktop\ComfyUI-Installs\ComfyUI\ComfyUI\main.py", line 221 in <module>


Additional verification inside the ComfyUI Desktop virtual environment:

Command:

cd "$env:LOCALAPPDATA\Comfy-Desktop\ComfyUI-Installs\ComfyUI\ComfyUI"
.\.venv\Scripts\python.exe -c "import torch; print(torch.__version__); print(torch.version.hip); print(torch.version.cuda)"

Output:

[WARNING] failed to run offload-arch: binary not found.
2.9.1+rocm7.2.1
7.2.53211-158bd99533
None


Command:

.\.venv\Scripts\python.exe -c "import torch; print(torch.cuda.is_available())"

Output:

[WARNING] failed to run offload-arch: binary not found.

The command does not print True or False.


Command:

.\.venv\Scripts\python.exe -m torch.utils.collect_env

Output:

[WARNING] failed to run offload-arch: binary not found.
<frozen runpy>:128: RuntimeWarning: 'torch.utils.collect_env' found in sys.modules after import of package 'torch.utils', but prior to execution of 'torch.utils.collect_env'; this may result in unpredictable behaviour
Collecting environment information...

The command does not complete with the expected environment report.


GPU information:

Command:

Get-CimInstance Win32_VideoController | Select-Object Name, DriverVersion

Output:

Name                  DriverVersion
----                  -------------
AMD Radeon RX 6900 XT 32.0.21043.12001

Browser Logs

Not available since the crash happens during backend startup before the ComfyUI web interface becomes usable, so I cannot collect browser console logs from the UI...

Settings JSON

No response

Other

This may be related to AMD/RDNA2 + Windows + bundled ROCm PyTorch inside ComfyUI Desktop.

The virtual environment contains a ROCm/HIP PyTorch build:

• torch: 2.9.1+rocm7.2.1
• torch.version.hip: 7.2.53211-158bd99533
• torch.version.cuda: None

However, GPU detection does not complete correctly. The command:

python -c "import torch; print(torch.cuda.is_available())"

does not return True or False, and ComfyUI Desktop crashes during startup with a Windows fatal access violation in torch.cuda.is_available().

It would be useful if ComfyUI Desktop could either support this AMD ROCm/RDNA2 setup correctly or detect the unsupported/broken configuration and show a clear error message instead of crashing.