React surfaces this error when a component tries to read a prop key that was never passed, which usually means a parent rendered the component with the wrong prop name or the child assumes data that does not exist.
The props object only contains whatever the parent explicitly provides plus React-controlled keys. When code reaches into props for a specific key that never arrived, React's development build raises this warning so you can correct a mismatch instead of silently running with undefined data.
Check the console warning and any stack trace to see which component and property trigger the message. Temporarily log props inside the component to see the actual object the component received, and note which key is absent.
Ensure the parent component passes the expected key with the correct name/case. If the prop is optional, guard the child and only read it when you know the data exists. When you rely on computed keys, verify that the lookup string stays in sync with the keys supplied through JSX.
Use PropTypes, TypeScript interfaces, or default props so tooling catches missing or mistyped keys before runtime. You can also provide fallback values (e.g., const value = props[keyName] ?? defaultValue) to keep the component from accessing undefined data.
React strips key and ref from the props object, so accessing them directly will always trigger this warning. In aggressively typed codebases, enabling strict prop checking or noImplicitAny makes these mismatches fail earlier. When dealing with dynamic prop names, consider normalizing the lookup key or using helper objects to avoid typos.
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