# ONNX004: unknown-node-input

**Code:** `ONNX004`

**Name:** `unknown-node-input`

**Severity:** error

**Category:** spec

**Target:** graph

**Fixable:** No

## Message

Node input is not produced by a previous node or a graph input.

## Suggestion

Ensure every node input is a graph input, initializer, or output of a preceding node.

## Details

Every input to a node must either be a graph input, an initializer,
or the output of a node that appears earlier in the graph.