⚠️ System Troubleshooting Guide
How to Fix "Prompt outputs failed validation" in ComfyUI
Troubleshoot missing model connections, disconnected node sockets, or unselected checkpoints.
Error Signature:
Prompt outputs failed validation: CLIP or VAE required input is missing⚡ Quick Direct Answer
Inspect red-highlighted nodes in your workflow. Verify all yellow (MODEL), orange (CLIP), and red (VAE) inputs are fully wired and file dropdowns have valid files selected.
Why Does This Error Happen?
A loader, sampler, or custom node has an empty dropdown selection (e.g. no checkpoint or VAE file selected in the UI) or a dangling wire not plugged into an input.
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Frequently Asked Questions
Why does ComfyUI highlight nodes with a red border?
A red border indicates the node cannot be validated before execution, typically because an input socket has no data wired to it or a model file dropdown is blank.