Hello,
I'm currently working on a NextJS App using pages routing. It was written back in the 12.x days and included a middleware.ts file. We have found that the middleware.ts file causes issues with our redirecting when a internal page is not found.
Example:
The page for a link has been deleted in the backend.
Prefetch returns a 404.
Clicking on the link redirects to a blank page.
Refreshing the page redirects to 404 page.

After deleting middleware.ts:
Clicking on the link redirects to 404 page.

I can not find any set documentation on how a middleware file should handle this sort of issue. Is there any way to send the prefetch result or make sure the response is a 404 and is treated as such in v12? I've seen a few solutions in v13. with for example notFound() but this is not available in 12.x.

Our middlware.ts file is very simple:

function middleware(req: NextRequest) {
let response = NextResponse.next()
response = allowIFrame(req, response)
return response
}


The allowIFrame function simply checks a few things in the method and path, it returns a slightly modified response, but leaves status uneffected.

Console.log(response) right after the let response = ... line gives the following on the 404 page:
{
cookies: {},
url: '',
body: null,
bodyUsed: false,
headers: { x-middleware-next: '1' },
ok: true,
redirected: false,
status: 200,
statusText: '',
type: 'default'
}

status is obviously wrong.

Does this mean middleware.ts should perform a prefetch or check before returning status? or is there a way to integrate a response from next/link that would allow for the response to correctly result in a 404?