unstable_rethrow

unstable_rethrow can be used to avoid catching internal errors thrown by Next.js when attempting to handle errors thrown in your application code.

For example, calling the notFound function will throw an internal Next.js error and render the not-found.js component. However, if used inside a try/catch block, the error will be caught, preventing not-found.js from rendering:

import { notFound } from 'next/navigation'
 
export default async function Page() {
  try {
    const post = await fetch('https://.../posts/1').then((res) => {
      if (res.status === 404) notFound()
      if (!res.ok) throw new Error(res.statusText)
      return res.json()
    })
  } catch (err) {
    console.error(err)
  }
}

You can use unstable_rethrow API to re-throw the internal error and continue with the expected behavior:

import { notFound, unstable_rethrow } from 'next/navigation'
 
export default async function Page() {
  try {
    const post = await fetch('https://.../posts/1').then((res) => {
      if (res.status === 404) notFound()
      if (!res.ok) throw new Error(res.statusText)
      return res.json()
    })
  } catch (err) {
    unstable_rethrow(err)
    console.error(err)
  }
}

The following Next.js APIs rely on throwing an error which should be rethrown and handled by Next.js itself:

• notFound()
• redirect()
• permanentRedirect()

If a route segment is marked to throw an error unless it's static, a Dynamic API call will also throw an error that should similarly not be caught by the developer. Note that Partial Prerendering (PPR) affects this behavior as well. These APIs are:

• cookies
• headers
• searchParams
• fetch(..., { cache: 'no-store' })
• fetch(..., { next: { revalidate: 0 } })

Good to know:

• This method should be called at the top of the catch block, passing the error object as its only argument. It can also be used within a .catch handler of a promise.
• If you ensure that your calls to APIs that throw are not wrapped in a try/catch then you don't need to use unstable_rethrow
• Any resource cleanup (like clearing intervals, timers, etc) would have to either happen prior to the call to unstable_rethrow or within a finally block.