Symptom

  • When you start ComfyUI, several (IMPORT FAILED) lines show up in the terminal, and certain custom nodes don't work or don't appear in the node list.

When it happens

  • Right after starting ComfyUI.
  • When custom nodes you installed don't show up in the node list.

Cause

  • A required library is missing, or you're using an unsupported Python / PyTorch version.
    • Scroll up from (IMPORT FAILED) in the terminal and you'll see something like ModuleNotFoundError: No module named 'facenet_pytorch', saying a library that custom node needs couldn't be found.
  • There's a path or OS-specific problem.
    • For example, non-ASCII characters (such as Japanese) in the folder path can cause errors like UnicodeDecodeError('cp932' codec can't decode byte 0x87...).
  • It conflicts with another custom node.
    • Nodes with older frontend code or their own unusual dependencies sometimes don't get along with newer ComfyUI and fail to load.

Solution

  • If libraries are missing

    • If you're comfortable with Python, you can pip install it yourself. Otherwise, first open that custom node's GitHub page and check that you installed it the right way.
    • These days, many nodes install all the libraries they need when installed through ComfyUI Manager. Unless you have a specific reason not to, install from Manager first.
    • If a node's README asks for special steps like "run this script manually" and you don't really understand them, don't touch that node in the first place.

  • If you suspect a conflict with another custom node

    • If you can, move every custom node except the one showing (IMPORT FAILED) out of custom_nodes, and check whether ComfyUI starts with only that node left.
    • Then bring the others back a little at a time, as "problem node + one other node," to find out which combination makes it fail.
    • If you don't need that node badly enough to go through all this, uninstall it (delete its whole folder).