Use a React Error Boundary to replace a failed part of the interface with fallback UI, then report the caught error from componentDidCatch. The boundary does not catch every frontend exception: event-handler failures, most asynchronous errors, server-rendering errors, and errors in the boundary itself need separate handling.
Build a boundary that renders a fallback and reports the failure
React documents two class lifecycle methods for an Error Boundary. static getDerivedStateFromError updates state so the next render can show fallback content; componentDidCatch is where you perform side effects such as sending a report. Keep the fallback decision separate from the reporting transport: React provides the boundary APIs, but your application must supply the endpoint or reporting service, payload format, delivery behavior, and storage.
import React from "react";
export class ErrorBoundary extends React.Component {
state = { hasError: false };
static getDerivedStateFromError(error) {
return { hasError: true };
}
componentDidCatch(error, info) {
const report = {
message:
error instanceof Error
? error.message
: String(error),
stack: error instanceof Error ? error.stack : undefined,
componentStack: info.componentStack,
occurredAt: new Date().toISOString(),
};
// Replace with your application's reviewed reporting transport.
void sendErrorReport(report).catch((reportingError) => {
console.error("Could not send error report", reportingError);
});
}
render() {
if (this.state.hasError) {
return this.props.fallback ?? This part of the page could not be displayed.
;
}
return this.props.children;
}
}
sendErrorReport is intentionally application-defined; it is not a React API. Its implementation should send data to a backend or a chosen error-reporting service and should account for network failure. Do not assume the report was delivered simply because componentDidCatch ran. Review the fields sent for sensitive information and avoid attaching user data that is not necessary.
React’s reference demonstrates reporting the error and info.componentStack from componentDidCatch: React Component reference.
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Choose a useful report payload
The caught value is not guaranteed to be an Error object. JavaScript permits throwing other values, so directly reading error.message or error.stack can fail or produce missing data. Normalize defensively, as in the example, and treat optional stack fields as optional.
- Error details: a safely normalized message and, when available, the JavaScript stack.
- Component context:
info.componentStackidentifies the component path associated with the failure. React notes that production component names may be minified; source maps can decode component stacks similarly to regular JavaScript stacks. - Operational context: an occurrence time or other carefully selected application context can help correlate reports. Any added fields are your application’s decision, not data React supplies through the boundary.
Keep the report useful without making it indiscriminate: component stacks can identify code paths, while application-added context can introduce privacy risks. Decide what to collect and how to retain it in your own reporting system.
Place boundaries around meaningful parts of the interface
A boundary lets a failed region fall back without necessarily replacing the entire page. Choose its position based on which part of the experience can be isolated and what fallback remains useful. React’s examples distinguish a boundary around a conversation list or an individual message—potentially meaningful regions—from wrapping every avatar, which is usually too fine-grained.
For example, a page might put a boundary around a primary content panel so that a rendering failure there does not remove unrelated navigation. Add nested boundaries only when separate sections genuinely need independent fallback behavior or reporting context; one boundary per component adds structure without automatically adding useful recovery.
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React’s guidance on Error Boundaries and boundary placement is in the Component reference.
Know what Error Boundaries do not catch
Error Boundaries catch errors thrown by descendant components during rendering. They are not a global exception handler. React lists these exclusions:
- Errors in event handlers, such as a click callback.
- Errors in most asynchronous callbacks, including
setTimeoutandrequestAnimationFrame. - Errors thrown while rendering on the server.
- Errors thrown by the boundary itself.
React documents an exception for errors thrown inside a startTransition function returned by useTransition. Do not generalize that exception to arbitrary asynchronous work.
A try/catch around a component’s JSX does not catch failures that occur later as React renders descendants. The React lint guidance explicitly recommends an Error Boundary for child rendering failures because ordinary try/catch cannot intercept React’s rendering process: React error-boundaries lint rule.
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Event handlers and asynchronous callbacks
Handle failures where the event or asynchronous operation runs. Use local try/catch for synchronous event-handler work and explicit rejection handling for promises; then report through the same application logging pipeline if appropriate. A boundary around the component does not turn these failures into render errors.
Server rendering
Server-rendering APIs provide their own error callbacks. React’s streaming renderers document onError for logging, and recommend continuing to log to the console when supplying a custom callback. With Suspense, some server render failures can result in fallback HTML while the client retries rendering. Consequently, onError can run even when rendering continues; it does not by itself mean the entire response failed.
See the React references for renderToReadableStream and renderToPipeableStream.
Recoverable errors in React 18 roots
React 18 added an onRecoverableError option to createRoot and hydrateRoot for logging errors React recovers from during rendering or hydration. This complements component-level boundary reporting; it is not a replacement for it. The behavior is described in the React 18 release notes.
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Keep reporting failures from obscuring the UI failure
Reporting is a side effect, while fallback rendering is the user’s immediate recovery path. Keep the fallback usable even if the network is unavailable or the reporting endpoint rejects the request. Decide how your application should handle retries, duplicate reports, and backend ingestion; React does not prescribe a transport or guarantee delivery.
When implementing against a particular installed React version, confirm the current API reference for that version. The cited React 18 release notes establish the root callback for React 18; they do not establish a broader version guarantee.
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