Refine the not-found rendering process for app router

packages/next/src/client/components/app-router.tsx

@@ -54,7 +54,6 @@ import { isBot } from '../../shared/lib/router/utils/is-bot'
 import { addBasePath } from '../add-base-path'
 import { AppRouterAnnouncer } from './app-router-announcer'
 import { RedirectBoundary } from './redirect-boundary'
-import { NotFoundBoundary } from './not-found-boundary'
 import { findHeadInCache } from './router-reducer/reducers/find-head-in-cache'
 import { createInfinitePromise } from './infinite-promise'
 import { NEXT_RSC_UNION_QUERY } from './app-router-headers'
@@ -89,24 +88,13 @@ export function urlToUrlWithoutFlightMarker(url: string): URL {
   return urlWithoutFlightParameters
 }
 
-const HotReloader:
-  | typeof import('./react-dev-overlay/hot-reloader-client').default
-  | null =
-  process.env.NODE_ENV === 'production'
-    ? null
-    : (require('./react-dev-overlay/hot-reloader-client')
-        .default as typeof import('./react-dev-overlay/hot-reloader-client').default)
-
 type AppRouterProps = Omit<
   Omit<InitialRouterStateParameters, 'isServer' | 'location'>,
   'initialParallelRoutes'
 > & {
   buildId: string
   initialHead: ReactNode
   assetPrefix: string
-  // Top level boundaries props
-  notFound: React.ReactNode | undefined
-  asNotFound?: boolean
 }
 
 function isExternalURL(url: URL) {
@@ -224,8 +212,6 @@ function Router({
   initialCanonicalUrl,
   children,
   assetPrefix,
-  notFound,
-  asNotFound,
 }: AppRouterProps) {
   const initialState = useMemo(
     () =>
@@ -445,16 +431,26 @@ function Router({
     return findHeadInCache(cache, tree[1])
   }, [cache, tree])
 
-  const notFoundProps = { notFound, asNotFound }
-
-  const content = (
+  let content = (
     <RedirectBoundary>
       {head}
       {cache.subTreeData}
       <AppRouterAnnouncer tree={tree} />
     </RedirectBoundary>
   )
 
+  if (process.env.NODE_ENV !== 'production') {
+    if (typeof window !== 'undefined') {
+      const DevRootNotFoundBoundary: typeof import('./dev-root-not-found-boundary').DevRootNotFoundBoundary =
+        require('./dev-root-not-found-boundary').DevRootNotFoundBoundary
+      content = <DevRootNotFoundBoundary>{content}</DevRootNotFoundBoundary>
+    }
+    const HotReloader: typeof import('./react-dev-overlay/hot-reloader-client').default =
+      require('./react-dev-overlay/hot-reloader-client').default
+
+    content = <HotReloader assetPrefix={assetPrefix}>{content}</HotReloader>
+  }
+
   return (
     <>
       <HistoryUpdater
@@ -484,16 +480,7 @@ function Router({
                   url: canonicalUrl,
                 }}
               >
-                {HotReloader ? (
-                  // HotReloader implements a separate NotFoundBoundary to maintain the HMR ping interval
-                  <HotReloader assetPrefix={assetPrefix} {...notFoundProps}>
-                    {content}
-                  </HotReloader>
-                ) : (
-                  <NotFoundBoundary {...notFoundProps}>
-                    {content}
-                  </NotFoundBoundary>
-                )}
+                {content}
               </LayoutRouterContext.Provider>
             </AppRouterContext.Provider>
           </GlobalLayoutRouterContext.Provider>

packages/next/src/client/components/dev-root-not-found-boundary.tsx

@@ -0,0 +1,25 @@
+'use client'
+
+import React from 'react'
+import { NotFoundBoundary } from './not-found-boundary'
+
+export function bailOnNotFound() {
+  throw new Error('notFound() is not allowed to use in root layout')
+}
+
+function NotAllowedRootNotFoundError() {
+  bailOnNotFound()
+  return null
+}
+
+export function DevRootNotFoundBoundary({
+  children,
+}: {
+  children: React.ReactNode
+}) {
+  return (
+    <NotFoundBoundary notFound={<NotAllowedRootNotFoundError />}>
+      {children}
+    </NotFoundBoundary>
+  )
+}

packages/next/src/client/components/layout-router.tsx

@@ -491,7 +491,6 @@ export default function OuterLayoutRouter({
   template,
   notFound,
   notFoundStyles,
-  asNotFound,
   styles,
 }: {
   parallelRouterKey: string
@@ -506,7 +505,6 @@ export default function OuterLayoutRouter({
   hasLoading: boolean
   notFound: React.ReactNode | undefined
   notFoundStyles: React.ReactNode | undefined
-  asNotFound?: boolean
   styles?: React.ReactNode
 }) {
   const context = useContext(LayoutRouterContext)
@@ -574,7 +572,6 @@ export default function OuterLayoutRouter({
                     <NotFoundBoundary
                       notFound={notFound}
                       notFoundStyles={notFoundStyles}
-                      asNotFound={asNotFound}
                     >
                       <RedirectBoundary>
                         <InnerLayoutRouter

packages/next/src/client/components/not-found-boundary.tsx

@@ -64,6 +64,9 @@ class NotFoundErrorBoundary extends React.Component<
       return (
         <>
           <meta name="robots" content="noindex" />
+          {process.env.NODE_ENV === 'development' && (
+            <meta name="next-error" content="not-found" />
+          )}
           {this.props.notFoundStyles}
           {this.props.notFound}
         </>

packages/next/src/client/components/react-dev-overlay/hot-reloader-client.tsx

@@ -10,7 +10,6 @@ import stripAnsi from 'next/dist/compiled/strip-ansi'
 import formatWebpackMessages from '../../dev/error-overlay/format-webpack-messages'
 import { useRouter } from '../navigation'
 import {
-  ACTION_NOT_FOUND,
   ACTION_VERSION_INFO,
   INITIAL_OVERLAY_STATE,
   errorOverlayReducer,
@@ -36,16 +35,13 @@ import {
 } from './internal/helpers/use-websocket'
 import { parseComponentStack } from './internal/helpers/parse-component-stack'
 import type { VersionInfo } from '../../../server/dev/parse-version-info'
-import { isNotFoundError } from '../not-found'
-import { NotFoundBoundary } from '../not-found-boundary'
 
 interface Dispatcher {
   onBuildOk(): void
   onBuildError(message: string): void
   onVersionInfo(versionInfo: VersionInfo): void
   onBeforeRefresh(): void
   onRefresh(): void
-  onNotFound(): void
 }
 
 // TODO-APP: add actual type
@@ -54,8 +50,6 @@ type PongEvent = any
 let mostRecentCompilationHash: any = null
 let __nextDevClientId = Math.round(Math.random() * 100 + Date.now())
 
-// let startLatency = undefined
-
 function onBeforeFastRefresh(dispatcher: Dispatcher, hasUpdates: boolean) {
   if (hasUpdates) {
     dispatcher.onBeforeRefresh()
@@ -422,18 +416,30 @@ function processMessage(
         fetch(window.location.href, {
           credentials: 'same-origin',
         }).then((pageRes) => {
-          if (pageRes.status === 200) {
-            // Page exists now, reload
-            startTransition(() => {
-              // @ts-ignore it exists, it's just hidden
-              router.fastRefresh()
-              dispatcher.onRefresh()
-            })
-          } else if (pageRes.status === 404) {
+          let shouldRefresh = pageRes.ok
+          // TODO-APP: investigate why edge runtime needs to reload
+          const isEdgeRuntime = pageRes.headers.get('x-edge-runtime') === '1'
+          if (pageRes.status === 404) {
+            // Check if head present as document.head could be null
             // We are still on the page,
             // dispatch an error so it's caught by the NotFound handler
-            dispatcher.onNotFound()
+            const devErrorMetaTag = document.head?.querySelector(
+              'meta[name="next-error"]'
+            )
+            shouldRefresh = !devErrorMetaTag
           }
+          // Page exists now, reload
+          startTransition(() => {
+            if (shouldRefresh) {
+              if (isEdgeRuntime) {
+                window.location.reload()
+              } else {
+                // @ts-ignore it exists, it's just hidden
+                router.fastRefresh()
+                dispatcher.onRefresh()
+              }
+            }
+          })
         })
       }
       return
@@ -450,15 +456,9 @@ function processMessage(
 export default function HotReload({
   assetPrefix,
   children,
-  notFound,
-  notFoundStyles,
-  asNotFound,
 }: {
   assetPrefix: string
   children?: ReactNode
-  notFound?: React.ReactNode
-  notFoundStyles?: React.ReactNode
-  asNotFound?: boolean
 }) {
   const [state, dispatch] = useReducer(
     errorOverlayReducer,
@@ -481,9 +481,6 @@ export default function HotReload({
       onVersionInfo(versionInfo) {
         dispatch({ type: ACTION_VERSION_INFO, versionInfo })
       },
-      onNotFound() {
-        dispatch({ type: ACTION_NOT_FOUND })
-      },
     }
   }, [dispatch])
 
@@ -505,9 +502,7 @@ export default function HotReload({
       frames: parseStack(reason.stack!),
     })
   }, [])
-  const handleOnReactError = useCallback((error: Error) => {
-    // not found errors are handled by the parent boundary, not the dev overlay
-    if (isNotFoundError(error)) throw error
+  const handleOnReactError = useCallback(() => {
     RuntimeErrorHandler.hadRuntimeError = true
   }, [])
   useErrorHandler(handleOnUnhandledError, handleOnUnhandledRejection)
@@ -538,15 +533,8 @@ export default function HotReload({
   }, [sendMessage, router, webSocketRef, dispatcher])
 
   return (
-    <NotFoundBoundary
-      key={`${state.notFound}`}
-      notFound={notFound}
-      notFoundStyles={notFoundStyles}
-      asNotFound={asNotFound}
-    >
-      <ReactDevOverlay onReactError={handleOnReactError} state={state}>
-        {children}
-      </ReactDevOverlay>
-    </NotFoundBoundary>
+    <ReactDevOverlay onReactError={handleOnReactError} state={state}>
+      {children}
+    </ReactDevOverlay>
   )
 }

packages/next/src/client/components/react-dev-overlay/internal/ReactDevOverlay.tsx

@@ -13,7 +13,6 @@ import { parseStack } from './helpers/parseStack'
 import { Base } from './styles/Base'
 import { ComponentStyles } from './styles/ComponentStyles'
 import { CssReset } from './styles/CssReset'
-import { notFound } from '../../not-found'
 
 interface ReactDevOverlayState {
   reactError: SupportedErrorEvent | null
@@ -59,10 +58,6 @@ class ReactDevOverlay extends React.PureComponent<
       reactError ||
       rootLayoutMissingTagsError
 
-    if (state.notFound) {
-      notFound()
-    }
-
     return (
       <>
         {reactError ? (

packages/next/src/client/components/react-dev-overlay/internal/error-overlay-reducer.ts

@@ -10,7 +10,6 @@ export const ACTION_REFRESH = 'fast-refresh'
 export const ACTION_UNHANDLED_ERROR = 'unhandled-error'
 export const ACTION_UNHANDLED_REJECTION = 'unhandled-rejection'
 export const ACTION_VERSION_INFO = 'version-info'
-export const ACTION_NOT_FOUND = 'not-found'
 export const INITIAL_OVERLAY_STATE: OverlayState = {
   nextId: 1,
   buildError: null,
@@ -34,10 +33,6 @@ interface FastRefreshAction {
   type: typeof ACTION_REFRESH
 }
 
-interface NotFoundAction {
-  type: typeof ACTION_NOT_FOUND
-}
-
 export interface UnhandledErrorAction {
   type: typeof ACTION_UNHANDLED_ERROR
   reason: Error
@@ -96,30 +91,25 @@ export const errorOverlayReducer: React.Reducer<
     | BuildErrorAction
     | BeforeFastRefreshAction
     | FastRefreshAction
-    | NotFoundAction
     | UnhandledErrorAction
     | UnhandledRejectionAction
     | VersionInfoAction
   >
 > = (state, action) => {
   switch (action.type) {
     case ACTION_BUILD_OK: {
-      return { ...state, buildError: null, notFound: false }
+      return { ...state, buildError: null }
     }
     case ACTION_BUILD_ERROR: {
       return { ...state, buildError: action.message }
     }
     case ACTION_BEFORE_REFRESH: {
       return { ...state, refreshState: { type: 'pending', errors: [] } }
     }
-    case ACTION_NOT_FOUND: {
-      return { ...state, notFound: true }
-    }
     case ACTION_REFRESH: {
       return {
         ...state,
         buildError: null,
-        notFound: false,
         errors:
           // Errors can come in during updates. In this case, UNHANDLED_ERROR
           // and UNHANDLED_REJECTION events might be dispatched between the