Not compatible with Flash ATTN 2.8.2

[hargret]

Module 'diffusers' load failed. If you don't have it installed, do it:
pip install diffusers

After I installed flash attn 2.8.2, both diffusers 0.34 and dev failed to start

[a-r-r-o-w]

Hi, this issue seems like a problem with your environment. Please try starting in a fresh environment and use something like uv instead of pip to manage versions easily

[hargret]

If there is a prompt, it only supports Flash ATTN 2.8.0, I didn't give a specific prompt, don't guess

[asomoza]

@hargret is hard to understand what you're saying, maybe write in your native language and then use a translator?

Anyways, diffusers works with flash-attn==2.8.2 without a problem, tested it and could generate an image.

Probably would be best, if you want help, to give a more detailed explanation of your issue, for example, a fully minimal reproducible snippet of code and your environment with diffusers-cli env

But I have the same opinion, this is something related to your environment and not diffusers.

[Trojaner]

It doesnt work with flash-attn 2.8.3 tho.

I am so confused on where this limit is defined, I was not able to find it in this repo.

[hargret]

The issue might be that I'm using Python 3.12.9. Below are the relevant messages. I don't know how to debug this step by step.

`## ComfyUI-Manager: installing dependencies done.
** ComfyUI startup time: 2025-08-24 15:29:35.011

** Platform:
Windows
** Python version:
3.12.9 (tags/v3.12.9:fdb8142, Feb 4 2025, 15:27:58) [MSC v.1942 64 bit (AMD64)]
** Python executable:
F:\ComfyUI-aki\python\python.exe
** ComfyUI Path:
F:\ComfyUI-aki
** ComfyUI Base Folder Path:

F:\ComfyUI-aki
** User directory:
F:\ComfyUI-aki\user
** ComfyUI-Manager config path:
F:\ComfyUI-aki\user\default\ComfyUI-Manager\config.ini
** Log path:
F:\ComfyUI-aki\user\comfyui.log

Prestartup times for custom nodes:
0.0 seconds: F:\ComfyUI-aki\custom_nodes\rgthree-comfy
0.0 seconds: F:\ComfyUI-aki\custom_nodes\ComfyUI-Easy-Use
7.4 seconds: F:\ComfyUI-aki\custom_nodes\ComfyUI-Manager

Checkpoint files will always be loaded safely.
Total VRAM 32607 MB, total RAM 63123 MB
pytorch version: 2.8.0+cu128
Set vram state to: NORMAL_VRAM
Disabling smart memory management
Device: cuda:0 NVIDIA GeForce RTX 5090 : native
Using pytorch attention
Python version: 3.12.9 (tags/v3.12.9:fdb8142, Feb 4 2025, 15:27:58) [MSC v.1942 64 bit (AMD64)]
ComfyUI version: 0.3.51
ComfyUI frontend version: 1.25.9
[Prompt Server] web root: F:\ComfyUI-aki\python\Lib\site-packages\comfyui_frontend_package\static
Config Export Error[Errno 2] No such file or directory: 'XXXHOST-PATHXXX\PATH_CFG.json'
Total VRAM 32607 MB, total RAM 63123 MB
pytorch version: 2.8.0+cu128
Set vram state to: NORMAL_VRAM
Disabling smart memory management
Device: cuda:0 NVIDIA GeForce RTX 5090 : native
Multiple distributions found for package optimum. Picked distribution: optimum
NumExpr defaulting to 16 threads.
Exception in thread Thread-10 (_readerthread)
:
Traceback (most recent call last):
File "F:\ComfyUI-aki\python\Lib\threading.py", line 1075, in _bootstrap_inner

self.run()
File "<enhanced_experience vendors.sentry_sdk.integrations.threading>", line 99, in run
File "<enhanced_experience vendors.sentry_sdk.integrations.threading>", line 94, in _run_old_run_func
File "<enhanced_experience vendors.sentry_sdk.utils>", line 1649, in reraise
File "<enhanced_experience vendors.sentry_sdk.integrations.threading>", line 92, in _run_old_run_func
File "F:\ComfyUI-aki\python\Lib\threading.py", line 1012, in run

self._target(*self._args, **self._kwargs)
File "F:\ComfyUI-aki\python\Lib\subprocess.py", line 1601, in _readerthread

buffer.append(fh.read())

^^
^^
^^
^^
^
File "", line 322, in decode
UnicodeDecodeError
: 'utf-8' codec can't decode byte 0xb2 in position 6: invalid start byte

�[33mModule 'diffusers' load failed. If you don't have it installed, do it:�[0m
�[33mpip install diffusers�[0m

`

[hargret]

After I uninstalled xformer 0.32, this issue disappeared.