fix: support non-prerendered dynamic routes with fallback false

packages/runtime/src/helpers/files.ts

@@ -333,8 +333,13 @@ const getServerFile = (root: string, includeBase = true) => {
   return findModuleFromBase({ candidates, paths: [root] })
 }
 
+// force manual revalidation so the ODB handler always receives fresh content
+// ensure fallback behaviour is bypassed for pre-rendered pages
+// ensure ISR 404 pages send the correct SWR cache headers
 const baseServerReplacements: Array<[string, string]> = [
-  [`let ssgCacheKey = `, `let ssgCacheKey = process.env._BYPASS_SSG || `],
+  [`checkIsManualRevalidate(req, this.renderOpts.previewProps)`, `checkIsManualRevalidate({ headers: null }, null)`],
+  [`isManualRevalidate && (fallbackMode !== false || hadCache)`, `isManualRevalidate && hadCache`],
+  [`private: isPreviewMode || is404Page && cachedData`, `private: isPreviewMode && cachedData`],
 ]
 
 const nextServerReplacements: Array<[string, string]> = [

packages/runtime/src/helpers/redirects.ts

@@ -14,6 +14,7 @@ import { RoutesManifest } from './types'
 import {
   getApiRewrites,
   getPreviewRewrites,
+  is404Route,
   isApiRoute,
   redirectsForNextRoute,
   redirectsForNextRouteWithData,
@@ -23,6 +24,14 @@ import {
 const matchesMiddleware = (middleware: Array<string>, route: string): boolean =>
   middleware.some((middlewarePath) => route.startsWith(middlewarePath))
 
+const generateHiddenPathRedirects = ({ basePath }: Pick<NextConfig, 'basePath'>): NetlifyConfig['redirects'] =>
+  HIDDEN_PATHS.map((path) => ({
+    from: `${basePath}${path}`,
+    to: '/404.html',
+    status: 404,
+    force: true,
+  }))
+
 const generateLocaleRedirects = ({
   i18n,
   basePath,
@@ -56,6 +65,54 @@ const generateLocaleRedirects = ({
   return redirects
 }
 
+const generate404Redirects = ({
+  staticRouteEntries,
+  basePath,
+  i18n,
+  buildId,
+}: {
+  staticRouteEntries: Array<[string, SsgRoute]>
+  basePath: string
+  i18n: NextConfig['i18n']
+  buildId: string
+}): NetlifyConfig['redirects'] => {
+  const redirects: NetlifyConfig['redirects'] = []
+
+  const isIsr404 = staticRouteEntries.some(
+    ([route, { initialRevalidateSeconds }]) => is404Route(route, i18n) && initialRevalidateSeconds !== false,
+  )
+
+  if (isIsr404) {
+    redirects.push({
+        from: `${basePath}/*`,
+        to: ODB_FUNCTION_PATH,
+        status: 404,
+      },
+    )
+  } else if (i18n?.locales?.length) {
+    i18n.locales.forEach((locale) => {
+      redirects.push({
+        from: `${basePath}/${locale}/*`,
+        to: `${basePath}/server/pages/${locale}/404.html`,
+        status: 404,
+      })
+    })
+    redirects.push({
+      from: `${basePath}/*`,
+      to: `${basePath}/server/pages/${i18n.defaultLocale}/404.html`,
+      status: 404,
+    })
+  } else {
+    redirects.push({
+      from: `${basePath}/*`,
+      to: `${basePath}/server/pages/404.html`,
+      status: 404,
+    })
+  }
+
+  return redirects
+}
+
 export const generateStaticRedirects = ({
   netlifyConfig,
   nextConfig: { i18n, basePath },
@@ -123,7 +180,7 @@ const generateStaticIsrRewrites = ({
   const staticRoutePaths = new Set<string>()
   const staticIsrRewrites: NetlifyConfig['redirects'] = []
   staticRouteEntries.forEach(([route, { initialRevalidateSeconds }]) => {
-    if (isApiRoute(route)) {
+    if (isApiRoute(route) || is404Route(route, i18n)) {
       return
     }
     staticRoutePaths.add(route)
@@ -191,13 +248,14 @@ const generateDynamicRewrites = ({
   const dynamicRewrites: NetlifyConfig['redirects'] = []
   const dynamicRoutesThatMatchMiddleware: Array<string> = []
   dynamicRoutes.forEach((route) => {
-    if (isApiRoute(route.page)) {
+    if (isApiRoute(route.page) || is404Route(route.page, i18n)) {
       return
     }
     if (route.page in prerenderedDynamicRoutes) {
+      const { fallback } = prerenderedDynamicRoutes[route.page]
       if (matchesMiddleware(middleware, route.page)) {
         dynamicRoutesThatMatchMiddleware.push(route.page)
-      } else {
+      } else if (fallback !== false) {
         dynamicRewrites.push(
           ...redirectsForNextRoute({ buildId, route: route.page, basePath, to: ODB_FUNCTION_PATH, status: 200, i18n }),
         )
@@ -231,14 +289,7 @@ export const generateRedirects = async ({
     join(netlifyConfig.build.publish, 'routes-manifest.json'),
   )
 
-  netlifyConfig.redirects.push(
-    ...HIDDEN_PATHS.map((path) => ({
-      from: `${basePath}${path}`,
-      to: '/404.html',
-      status: 404,
-      force: true,
-    })),
-  )
+  netlifyConfig.redirects.push(...generateHiddenPathRedirects({ basePath }))
 
   if (i18n && i18n.localeDetection !== false) {
     netlifyConfig.redirects.push(...generateLocaleRedirects({ i18n, basePath, trailingSlash }))
@@ -274,7 +325,7 @@ export const generateRedirects = async ({
 
   // Add rewrites for all static SSR routes. This is Next 12+
   staticRoutes?.forEach((route) => {
-    if (staticRoutePaths.has(route.page) || isApiRoute(route.page)) {
+    if (staticRoutePaths.has(route.page) || isApiRoute(route.page) || is404Route(route.page)) {
       // Prerendered static routes are either handled by the CDN or are ISR
       return
     }
@@ -294,12 +345,7 @@ export const generateRedirects = async ({
   netlifyConfig.redirects.push(...dynamicRewrites)
   routesThatMatchMiddleware.push(...dynamicRoutesThatMatchMiddleware)
 
-  // Final fallback
-  netlifyConfig.redirects.push({
-    from: `${basePath}/*`,
-    to: HANDLER_FUNCTION_PATH,
-    status: 200,
-  })
+  netlifyConfig.redirects.push(...generate404Redirects({ staticRouteEntries, basePath, i18n, buildId }))
 
   const middlewareMatches = new Set(routesThatMatchMiddleware).size
   if (middlewareMatches > 0) {

packages/runtime/src/helpers/utils.ts

@@ -73,6 +73,9 @@ const netlifyRoutesForNextRoute = (route: string, buildId: string, i18n?: I18n):
 
 export const isApiRoute = (route: string) => route.startsWith('/api/') || route === '/api'
 
+export const is404Route = (route: string, i18n?: I18n) =>
+  i18n ? i18n.locales.some((locale) => route === `/${locale}/404`) : route === '/404'
+
 export const redirectsForNextRoute = ({
   route,
   buildId,