Asset URLs with old hash 500 when you visit them instead of 404 in production

[timteeling]

• I have searched the issues of this repository and believe that this is not a duplicate.

Expected Behavior

If a user happens to request an old bundle resource with an old hash, the response should 404, not 500.

Current Behavior

I'm currently running a Next.js app at https://www.tenable.com/plugins and I'm getting quite a few 500 errors in my logs after I deploy a new version that has a new hash from the build (I'm using sticky sessions to minimize the disruption, but still see some errors long after the deploy).

Steps to Reproduce (for bugs)

200 -> https://custom-server-koa-wxksegmzhf.now.sh/_next/7c048a193f99703d6180e88866b6e06b/app.js

500 Internal server error -> https://custom-server-koa-wxksegmzhf.now.sh/_next/OLD_HASH_VALUE/app.js

Source code area of interest: https://github.com/zeit/next.js/blob/1aade36f13e03db13d23f86dc52a459f9a29e03d/server/index.js#L467

Context

Just trying to minimize the number of unneeded 500 errors 😄

Appreciate all your work and effort!

Your Environment

Tech	Version
next	canary
node	8.9
OS	macOS, node docker
browser
etc

[rovansteen]

Well actually the status code is a 200. It would be great if it would return a non successful status code. I use Cloudflare to cache all my static assets and right now it caches the '500' one because it thinks it's a 200. I assume these assets are all unique due to their ID so I cache them for a month which has a big chance of breaking my site during rolling deployments.

[timteeling]

Think this tweak to handleBuildHash would take care of setting the status correctly in production when the hash doesn't match? Would it be okay if I opened a PR with this?

handleBuildHash (filename, hash, res) {
  if (this.dev) {
    res.setHeader('Cache-Control', 'no-store, must-revalidate')
    return true
  }

  if (hash !== this.buildStats[filename].hash) {
    if (this.dev) {
      throw new Error(`Invalid Build File Hash(${hash}) for chunk: ${filename}`)
    }

    this.send404(res);
  }

  res.setHeader('Cache-Control', 'max-age=31536000, immutable')
  return true
}