Cannot execute because a node is missing the class_type property.: Node ID '#7'

[Tipmt]

Feature Idea

Cannot execute because a node is missing the class_type property.: Node ID '#7'

Existing Solutions

No response

Other

No response

[christian-byrne]

Are there any other details you can provide, such as workflow, browser console logs, terminal logs, software version, etc.?

[RomixERR]

Similar problem, with almost any workflow

[christian-byrne]

This issue has been addressed with improved error messaging in frontend v1.39.5 (backend: #12177, frontend: Comfy-Org/ComfyUI_frontend#8511).

The cryptic "Cannot execute because a node is missing the class_type property" error now shows:

• The actual node type (e.g., KSampler, LoadImage) that is missing
• The node's custom title if you renamed it in the workflow
• A hint to install missing custom nodes via ComfyUI Manager

To get the fix: Update frontend to v1.39.5+ or use --front-end-version Comfy-Org/ComfyUI_frontend@1.39.5. ComfyUI Desktop users will receive this in the next stable release (~mid-February 2026).

If the node source shows "Unknown": This happens when the Manager is not installed or the node is not in the registry. You can enable the built-in Manager with --enable-manager, use the legacy Manager UI with --enable-manager --enable-manager-legacy-ui, or install ComfyUI-Manager as a custom node. The node ID in the error message can still help you locate it in the workflow.

Feel free to reopen this issue if the problem persists after updating. Please include your ComfyUI version, frontend version (visible in bottom-right corner), and a screenshot of the error dialog.

For general guidance see https://docs.comfy.org, or contact support@comfy.org for additional help.