Warning: Support for defaultProps will be removed from function components in a future major release.
A function component (often inside a library) uses Component.defaultProps.
Exact message you may see
Support for defaultProps will be removed from function components
Seen on:
React
Meaning
React 18.3 warns; React 19 removes defaultProps for function components. Use JavaScript default parameters instead.
Common causes
- Your components using defaultProps
- Old library versions using defaultProps
⚡ Quick fix
- Use default parameters: function Btn({ size = 'md' })
- Upgrade libraries
Detailed fix by platform
React
function Avatar({ size = 40, alt = '' }) { … }
How to diagnose
- Source — Your code or a library?
- Recent change — Did it start after a deploy, upgrade, or configuration change? Compare with the last working version.
🔧 Still not fixed?
Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:
Similar errors
Most viewed in React
- Objects are not valid as a React child Error: Objects are not valid as a React child
- No QueryClient set Error: No QueryClient set, use QueryClientProvider to set one
- Functions cannot be passed Error: Functions cannot be passed directly to Client Components unless you explicitly expose it by marking it with "use server".
Other ways to find it
Where this error sits
Origin: On your device. Errors that are often confused with or caused by this one (click to open):
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Last updated 14 Oct 2026