Error messages

(IMPORT FAILED)

(IMPORT FAILED)

Near the end of ComfyUI's startup log there's a list of every custom node pack with how long it took to load. A pack that broke gets a flag in that list:

Import times for custom nodes:
   0.0 seconds: C:\ComfyUI\custom_nodes\websocket_image_save.py
   0.4 seconds (IMPORT FAILED): C:\ComfyUI\custom_nodes\ComfyUI-PuLID-Flux-Enhanced
   1.2 seconds: C:\ComfyUI\custom_nodes\ComfyUI-Manager

The paths and times there are illustrative; the format is copied from the code. It's by far the most pasted ComfyUI line we looked at: 501 issues in the Comfy-Org/ComfyUI repo contain "IMPORT FAILED" as of September 26, 2026. Most of them paste only this list, which doesn't say what went wrong.

Where the actual error is

We read nodes.py in ComfyUI 0.37.0. For each folder in custom_nodes, ComfyUI imports the pack's __init__.py like any Python module. If that raises anything, it prints the full Python traceback and then one line naming the pack and the exception:

Cannot import C:\ComfyUI\custom_nodes\ComfyUI-PuLID-Flux-Enhanced module for custom nodes: No module named 'insightface.app'

Only later does the summary mark it (IMPORT FAILED). So scroll up and search the log for the pack's folder name. The text after the colon is the reason. A request to put it in the summary line too (ComfyUI_frontend #12450) was still open on September 26, 2026.

There's one quieter case: a pack that imports fine but exports no nodes gets "Skip ... module for custom nodes due to the lack of NODE_CLASS_MAPPINGS or comfy_entrypoint", which is also counted as a failed import. That usually means a half-downloaded folder or something that isn't a node pack at all.

Missing Python packages, and which Python gets them

The usual reason is No module named '...': the pack needs a library that isn't installed. Install the pack's requirements from its folder, but with the Python that ComfyUI runs on. On the Windows portable build that's the bundled one. ltdrdata, a ComfyUI maintainer, told one user in #6725 to run pip from the python_embeded folder and stressed that it "Must use .\python.exe not python.exe" (plain python is whatever Python your system finds first). For example:

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

Some packs need compiled wheels (insightface, llama-cpp-python) that have to match your Python version, and the ComfyUI troubleshooting docs also blame packs that pin a strict version of something like torch which clashes with another pack. Those end up in the pack's own issue tracker, and that's where maintainers send them: "Please move this issue to ComfyUI-PuLID-Flux-Enhanced repo" (#5461).

When a built-in node fails instead

ComfyUI's own extra nodes use a different message with no brackets:

WARNING: some comfy_extras/ nodes did not import correctly. This may be because they are missing some dependencies.

IMPORT FAILED: nodes_video.py

That one follows an update which added a dependency. The log says to run pip install -r requirements.txt in the ComfyUI folder (or update/update_comfyui.bat on the portable build). For nodes_video.py in #6970, the missing package was av.

Finding a pack that breaks everything

If a failing pack takes ComfyUI down with it, start with --disable-all-custom-nodes, which the ComfyUI docs recommend before switching packs back on half at a time. Renaming one pack's folder so it ends in .disabled also makes ComfyUI skip it at startup.