Removed page from Middleware API

Why This Error Occurred

Your application is interacting with request.page which has been deprecated.

import { NextRequest, NextResponse } from 'next/server'

export function middleware(request: NextRequest) {
  const { params } = event.request.page
  const { locale, slug } = params

  if (locale && slug) {
    const { search, protocol, host } = request.nextUrl
    const url = new URL(`${protocol}//${locale}.${host}/${slug}${search}`)
    return NextResponse.redirect(url)
  }
}

Possible Ways to Fix It

You can use URLPattern instead to have the same behavior:

import { NextRequest, NextResponse } from 'next/server'

const PATTERNS = [
  [
    new URLPattern({ pathname: '/:locale/:slug' }),
    ({ pathname }) => pathname.groups,
  ],
]

const params = (url) => {
  const input = url.split('?')[0]
  let result = {}

  for (const [pattern, handler] of PATTERNS) {
    const patternResult = pattern.exec(input)
    if (patternResult !== null && 'pathname' in patternResult) {
      result = handler(patternResult)
      break
    }
  }
  return result
}

export function middleware(request: NextRequest) {
  const { locale, slug } = params(request.url)

  if (locale && slug) {
    const { search, protocol, host } = request.nextUrl
    const url = new URL(`${protocol}//${locale}.${host}/${slug}${search}`)
    return NextResponse.redirect(url)
  }
}