If you are creating a dynamic page eg: product/[slug].tsx then even if you don't want to create any page on build time you need to create a getStaticPaths method to set the fallback property and let NextJS know what to do when the page you are trying to get doesn't exist.

export const getStaticPaths: GetStaticPaths<{ slug: string }> = async () => {

    return {
        paths: [], //indicates that no page needs be created at build time
        fallback: 'blocking' //indicates the type of fallback
    }
}

getStaticPaths does mainly two things:

• Indicate which paths should be created on build time (returning a paths array)

• Indicate what to do when a certain page eg: "product/myProduct123" doesn't exist in the NextJS Cache (returning a fallback type)

Dynamic Routing Next Js

pages/users/[id].js

import React from 'react'

const User = ({ user }) => {
  return (
    <div className="row">
      <div className="col-md-6 offset-md-3">
        <div className="card">
          <div className="card-body text-center">
            <h3>{user.name}</h3>
            <p>Email: {user.email} </p>
          </div>
        </div>
      </div>
    </div>
  )
}

export async function getStaticPaths() {
  const res = await fetch('https://jsonplaceholder.typicode.com/users')
  const users = await res.json()

  const paths = users.map((user) => ({
    params: { id: user.id.toString() },
  }))

  return { paths, fallback: false }
}


export async function getStaticProps({ params }) {
  const res = await fetch(`https://jsonplaceholder.typicode.com/users/${params.id}`)
  const user = await res.json()

  return { props: { user } }
}

export default User

if you are using getStaticPaths, you are telling next.js that you want to pregenerate that page. However since you used it inside a dynamic page, next.js does not know in advance how many pages it has to create.

with getStaticPaths, we fetch the database. If we are rendering blogs, we fetch the database to decide how many blogs we have, what would be idOfBlogPost and then based on this information, getStaticPath will pre-generate pages.

also, getStaticProps does not run only during the build time. If you add revalidate:numberOfSeconds, next.js will recreate new page with fresh data after "numberOfSeconds" time.

For rendering dynamic route use getServerSideProps() instead of getStaticProps()

For Example:

export async function getServerSideProps({
locale,
}: GetServerSidePropsContext): Promise<GetServerSidePropsResult<Record<string, unknown>>> {

return {
    props: {
        ...(await serverSideTranslations(locale || 'de', ['common', 'employees'], nextI18nextConfig)),
    },
  }
}

You can check here as well