Error: Missing or invalid getServerSideProps return in Next.js: Causes and How to Fix

Ensure Proper Return Structure

• Ensure that the getServerSideProps function returns an object with a props key. The props key must itself be an object.

 

• If you intend to return parameters through URL query strings, structure them within the props object.

export async function getServerSideProps(context) {
  return {
    props: {} // Ensure that this object structure is maintained
  };
}

Handle Errors Gracefully

• Incorporate error handling within the getServerSideProps. Return a fallback or alternative data structure if the main data request fails.

 

• Make use of try-catch blocks to manage errors effectively and prevent invalid or missing returns from breaking your application.

export async function getServerSideProps(context) {
  try {
    const data = await fetchDataFromAPI();
    return {
      props: { data }
    };
  } catch (error) {
    console.error('Data fetching error:', error);
    return {
      props: { error: 'Failed to fetch data' }
    };
  }
}

Verify the Function's Return Path

• Check every possible execution path to confirm that they all lead to a valid return structure in getServerSideProps. Missing a return statement may result in this error.

 

• Utilize conditionals properly to ensure they will execute a return under all logic branches.

export async function getServerSideProps(context) {
  if (someCondition) {
    return {
      props: { message: 'Condition met' }
    };
  } else {
    return {
      props: { message: 'Condition not met' }
    };
  }
}

Check Redirects and Rewrites

• Avoid returning non-object values from the function. Instead, if you need to redirect or render an error page, use the appropriate Next.js methods.

 

• When a redirect is necessary, return an object containing the redirect property.

export async function getServerSideProps(context) {
  const { query } = context;
  if (!query.valid) {
    return {
      redirect: {
        destination: '/error',
        permanent: false
      }
    };
  }

  return {
    props: { query }
  };
}

Utilize Type Checking

• Incorporate TypeScript to help identify structural issues early by defining the expected return type of the getServerSideProps function.

 

• This can prevent errors related to an incorrect structure of the returned object at compile time instead of runtime.

import { GetServerSideProps } from 'next';

export const getServerSideProps: GetServerSideProps = async (context) => {
  const data = await someAsyncOperation();
  return { props: { data } };
};