- Introduces error boundaries, support for returning arrays/strings from render, portals, and streaming server‑side rendering APIs.
- Adds breaking changes to lifecycle methods, setState semantics, ref handling, container unmounting behavior, and introduces a new hydrate API for server‑rendered markup.
- Removes the legacy react‑with‑addons build, moves UMD build paths, and encourages using separate npm packages for addons.
Community impact
Community ratings: 0 Useful, 0 Noise, 0 Risky, 0 Broke, 0 Try.