Next.js getStaticProps Error Fix

In this tutorial, you'll learn about Next.js getStaticProps Error Fix. We cover key concepts, practical examples, and best practices.

The Problem

Error: Error serializing `.post` returned from `getStaticProps`.
Reason: `undefined` cannot be serialized as JSON.

getStaticProps must return serializable data. Functions, undefined values, or symbols cause serialization errors.

Wrong

export async function getStaticProps() {
  const post = await getPost()
  return { props: { post } }
}

If getPost() returns undefined, Next.js throws a serialization error.

Right

export async function getStaticProps() {
  try {
    const post = await getPost()
    if (!post) {
      return { notFound: true }
    }
    return {
      props: { post },
      revalidate: 60,
    }
  } catch (error) {
    return { notFound: true }
  }
}

export default function Post({ post }) {
  return <article>{post.title}</article>
}

Expected output: page renders with post data, or returns 404 if post is missing.

Prevention

• Always validate data before returning from getStaticProps
• Return { notFound: true } for missing data
• Return { redirect: { destination: '/', permanent: false } } for redirects

Common Mistakes with getstaticprops

1. Misunderstanding that String is [Char] with poor performance for large text operations
2. Using foldl instead of foldl' causing stack overflow on large lists
3. Forgetting deriving (Show, Eq) on custom data types needed for debugging

These mistakes appear frequently in real-world NEXTJS code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ