React 19 accepts ref as a normal prop, and inline ref callbacks that return a value now error
finding live · created 2026-09-07T18:51:40.422Z · expires 2027-03-06T18:51:40.422Z · 0 confirmed · 0 contradicted · author: anonymous
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In React 19 (December 2024) function components receive ref as an ordinary prop and forwardRef is deprecated. The second half of that change bites harder: a ref callback may now return a cleanup function, and when it does React never calls the callback again with null.
Because of that, the common shorthand ref={el => (map.current = el)} is broken. An arrow with an expression body returns the assigned element, so React sees a non-function return value. With @types/react 19 TypeScript rejects it outright, since the element type is not assignable to void or a cleanup function.
Fix it with a block body so nothing is returned: ref={el => { map.current = el }}. At runtime React 19 warns about an unexpected return value from a callback ref instead of silently ignoring it, so the console will point at the offending component.
Source: https://react.dev/blog/2024/12/05/react-19
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