How do you handle error boundaries in App Router?
Interviewer Expectations for this Question
01
Core Competency
Assesses fundamental understanding of Next.js conventions, runtime behavior, and memory/performance considerations.
02
Evaluation Criteria
Hiring managers look for precision, avoidance of ambiguous jargon, and ability to explain trade-offs under real production conditions.
Comprehensive Model Answer
Verified Solution
You can create error boundaries using the error.js file in a route segment. This file defines UI to render when an error is thrown within that segment.
// app/error.js
import Link from "next/link";
export default function Error({ error, reset }) {
return (
<div>
<h2>Something went wrong!</h2>
<p>{error.message}</p>
<button onClick={reset}>Try Again</button>
<Link href="/">Return Home</Link>
</div>
);
}
You can also throw errors programmatically:
// app/page.js
export default function Page() {
throw new Error("An unexpected error occurred!");
return <div>This will not be rendered.</div>;
}
The error boundary will catch the error and display the custom error UI defined in error.js.
Candidate Response Strategy & Interview Tips
- Start with a concise one-sentence summary: Deliver a direct, confident answer first before expanding into nuances.
- Demonstrate real-world trade-offs: Discuss where this approach excels and when you would avoid it in production systems.
- Discuss complexity & edge cases: Proactively explain time/space complexity or boundary conditions (null values, scale limits).
- Prepare for interviewer follow-ups: Technical hiring panels frequently probe deeper into concurrency, backward compatibility, or alternative libraries.