What it means
ComfyUI loaded a workflow that calls node types it does not have registered. Those nodes come from custom-node packages that are not present in your installation, so ComfyUI marks them red and refuses to queue the prompt until they resolve.
This is expected when you open someone else’s workflow, or one made in a newer setup: the JSON only records which nodes to use, not the code behind them. You need to install the packages that provide those node types.
Common causes
- The custom-node package that defines the node is not installed.
- The workflow came from another machine with different extensions.
- A node was renamed or removed in a newer version of its package.
- The package is installed but failed to import (see the separate import-failed error).
How to fix it
- 1
Use the Manager to install missing nodes
Open ComfyUI Manager and choose "Install Missing Custom Nodes". It reads the red node types and offers the packages that provide them.
- 2
Install by hand if the Manager cannot find it
Git-clone the node’s repository into ComfyUI/custom_nodes, install its requirements.txt into the same Python environment, then restart.
- 3
Restart ComfyUI and reload the workflow
Custom nodes register at startup. After installing, fully restart the server and reload the graph so the previously-red nodes resolve.
- 4
Check for a renamed node
If a node no longer exists in the current package, check the repo’s changelog for a replacement node and swap it into the graph.
Keeping a workflow alongside the list of custom-node packages it depends on means a graph that ran today can be rebuilt on another machine without hunting down which extensions were required.
Frequently asked questions
Frequently Asked Questions
Quick answers to the most common questions.
Related errors
Make every ComfyUI run reproducible
Numonic captures the full workflow behind each ComfyUI generation — models, samplers, seeds, prompts, and custom nodes — so a setup that finally works is one you can find and rebuild, not re-debug.