React Error Boundaries

Quick Guide: A boundary catches errors thrown during render, in lifecycle methods and in constructors, and swaps the subtree for fallback UI. It never sees event-handler, async or server-render errors — those reach it only when something calls showBoundary(). Boundaries are class components, because getDerivedStateFromError and componentDidCatch have no hook equivalent. React 19 adds onCaughtError, onUncaughtError and onRecoverableError on createRoot, which log rather than render and are silently ignored on React 18.

Detailed Resources:

• examples/core.md — the class boundary, react-error-boundary usage, resetKeys, useErrorBoundary, granular placement
• examples/react-19-hooks.md — createRoot/hydrateRoot error options, captureOwnerStack(), error filtering
• examples/recovery.md — retry limits, exponential backoff, error classification
• examples/testing.md — what makes a boundary testable, and the fixtures that do it
• reference.md — what boundaries catch, lifecycle and prop tables, checklists

Which path applies