This is a reference entry from React error codes. A full explanation with fixes has not been written yet.
Hydration failed because the server rendered %s didn't match the client. As a result this tree will be regenerated on the client. This can happen if a SSR-ed Client Component used: - A server/client branch `if (typeof window !== 'undefined')`. - Variable input such as `Date.now()` or `Math.random()` which changes each time it's called. - Date formatting in a user's locale which doesn't match the server. - External changing data without sending a snapshot of it along with the HTML. - Invalid HTML tag nesting. It can also happen if the client has a browser extension installed which messes with the HTML before React loaded. https://react.dev/link/hydration-mismatch%s
%s is filled in by React at runtime.
- Category
- Minified React error
- Severity
- error
- Runtime
- both
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Source: React error codes. Data fetched 2026-09-25T01:43:12.929Z.