No module named 'diffusers' in ComfyUI

If ComfyUI logs ModuleNotFoundError: No module named 'diffusers', a custom node that depends on the Hugging Face Diffusers library cannot load.

ComfyUI itself does not require diffusers. This error comes from third-party custom nodes that use the Diffusers pipeline for model loading, conversion, or inference. Common examples include nodes for Stable Diffusion pipelines, IP-Adapter, AnimateDiff, or model conversion utilities.

.\python_embeded\python.exe -s -m pip install diffusers
.\python_embeded\python.exe -s ComfyUI\main.py --windows-standalone-build

What the error looks like

IMPORT FAILED: ComfyUI-ExampleNode
Traceback (most recent call last):
  File "...\custom_nodes\ComfyUI-ExampleNode\__init__.py", line 3, in <module>
    from diffusers import StableDiffusionPipeline
ModuleNotFoundError: No module named 'diffusers'

The exact custom node name will vary. The key indicator is No module named 'diffusers' in the traceback.

Why it happens

• The custom node was installed (cloned or downloaded) but its requirements.txt was never run
• ComfyUI Manager installed the node files but did not install Python dependencies
• You reinstalled or updated ComfyUI and the new environment does not have diffusers
• A previous pip install broke the package and it was silently uninstalled during conflict resolution

Quick diagnosis

Safe manual fix

Step 1: Install diffusers in the correct Python

For Windows portable:

.\python_embeded\python.exe -s -m pip install diffusers

For a manual venv:

python -m pip install diffusers

This will also install dependencies like safetensors, huggingface-hub, and regex if they are not already present.

Step 2: If the custom node has its own requirements.txt

Check the plugin folder for a requirements file:

Get-Content ComfyUI\custom_nodes\<node-name>\requirements.txt

If it exists, install from it, but read it first to make sure it will not downgrade torch or other core packages:

.\python_embeded\python.exe -s -m pip install -r ComfyUI\custom_nodes\<node-name>\requirements.txt

Step 3: Restart and verify

.\python_embeded\python.exe -s ComfyUI\main.py --windows-standalone-build

Check the startup log. The IMPORT FAILED line for that node should be gone.

When not to run pip install blindly

diffusers has many dependencies and updates frequently. Be careful about:

• Installing a version that conflicts with your current transformers or torch version
• Running pip install diffusers --upgrade when a custom node needs a specific version
• Installing diffusers[torch] extras that might pull a CPU-only torch build

If pip check shows conflicts after installing, fix the specific version mismatch rather than upgrading everything.

How Wonderful Launcher can help

Wonderful Launcher can help detect and resolve this issue. It helps manage your ComfyUI environment and dependencies safely, reducing the risk of version conflicts that diffusers updates can cause.

Download Wonderful Launcher — it's free and can recover your environment without reinstalling.

Related errors

• ComfyUI Plugin Import Failed
• ComfyUI Transformers Missing
• ComfyUI Dependency Conflicts
• Plugin Missing Module Warning: When It Is Safe to Ignore
• ComfyUI Startup Failed

Source References

• diffusers on PyPI
• Hugging Face Diffusers GitHub
• ComfyUI GitHub