ComfyUI Plugin Import Failed: Fix Custom Node Errors

If the startup log shows IMPORT FAILED, a custom node was downloaded but the Python process that starts ComfyUI could not import it. Identify the exact plugin and traceback first, fix the earliest import failure (not the red node you noticed later), and install packages only in the Python environment that launches ComfyUI. This is a dependency or packaging problem first — not proof that all of ComfyUI is broken.

If the visible error is different, use the matching guide instead: Failed to Save Workflow Draft → save the workflow JSON first; failed to fetch server logs → Failed to Fetch Server Logs; Manager failed to get custom node list → Failed to Get Custom Node List.

Typical log lines:

IMPORT FAILED: ComfyUI-ExampleNode
ModuleNotFoundError: No module named 'somepackage'

IMPORT FAILED: ComfyUI-AnotherNode
ImportError: DLL load failed while importing cv2

IMPORT FAILED: ComfyUI-SomePlugin
AttributeError: module 'torch' has no attribute '...'

Separate three symptoms that get mixed together

Fix the earliest failing layer first. Installing packages for a runtime error will not help if the plugin never registered its nodes.

Triage: package-specific routes

If the traceback names one of these, use the narrow guide before running broad plugin requirements:

Step 1: Confirm which plugin actually failed

Do not start by installing random packages. Answer: which plugin failed, and what error type stopped the import? Check in order:

• Startup log: find IMPORT FAILED and copy the full traceback.
• Import failure API: if the UI opens, visit http://127.0.0.1:8188/v2/customnode/import_fail_info_bulk for a JSON list of failures.
• Workflow symptoms: note whether one plugin family is missing, multiple unrelated plugins are missing, or a plugin worked before another install changed the environment.

Step 2: Classify the failure before you fix it

• Missing package (ModuleNotFoundError: No module named 'onnxruntime') — the plugin expects a package that is not installed.
• Broken binary package (ImportError: DLL load failed while importing cv2) — the wheel does not match your Python, CUDA, or Windows runtime.
• Core dependency drift (AttributeError: module 'torch' has no attribute '...') — another plugin install changed torch, numpy, pillow, or opencv-python.
• Repo or source problem — the repo moved, cloned partially, left Git LFS pointers, or is too old for your ComfyUI version.

Before any install command, check: did the plugin ever work here; is the folder present but broken or completely missing; did another plugin install happen right before this started failing.

Step 3: Repair with the narrowest fix

If a package is missing, install it in the Python that starts ComfyUI:

If you suspect dependency drift, run pip check and look for conflicts around torch, torchvision, torchaudio, numpy, pillow, opencv-python, transformers, diffusers. Repair the core package first, then retest. See ComfyUI Dependency Conflicts.

If the plugin itself is outdated or partially broken, verify the repo is correct, the source files are real code (not Git LFS pointers), and the plugin still supports your ComfyUI version. If needed, cd custom_nodes/<plugin-name> and git pull, then reinstall only that plugin's requirements:

For the official Windows portable package, run from the portable root with .\python_embeded\python.exe -s -m pip install -r .\ComfyUI\custom_nodes\<plugin-name>\requirements.txt.

Verification ladder

A plugin folder, a successful clone, or an offline Python import is not the same as a working ComfyUI node. Confirm each rung before calling the repair done:

If nodes now register but the workflow asks for model files, switch to model placement or cannot find model instead of reinstalling the plugin.

When this is really a dependency-conflict problem

If one plugin import failure turns into several unrelated plugin failures after a package install, switch to:

• ComfyUI Dependency Conflicts
• Repair ComfyUI Portable Dependencies One Missing Module At A Time

Related guides

• ComfyUI Startup Failed? How to Diagnose and Recover Faster
• ComfyUI Dependency Conflicts
• ComfyUI No Module Named Error: When It Is Safe to Ignore
• ComfyUI No Module Named 'llama_cpp'
• ComfyUI Plugin Management
• Popular ComfyUI Custom Node Packs
• Troubleshooting Decision Tree

Source References

• ComfyUI troubleshooting overview
• ComfyUI custom node troubleshooting guide
• ComfyUI model troubleshooting guide
• ComfyUI Manager installation guide