Fix: Legacy fallback env var

README.md

@@ -89,6 +89,10 @@ The Next.js Runtime fully supports ISR on Netlify. For more details see
 
 Note that Netlify has a minimum TTL of 60 seconds for revalidation.
 
+## Disable Static 404 on Dynamic Routes with fallback:false
+
+Currently when hitting a non-prerendered path with `fallback=false` it will default to a 404 page. You can now change this default setting by using the environemnt variable `LEGACY_FALLBACK_FALSE=true`. With the environment variable set, those non-prerendered paths will now be routed through using the ISR Handler and will allow you to add redirects for those non-prerendered paths. 
+
 ## Use with `next export`
 
 If you are using `next export` to generate a static site, you do not need most of the functionality of this Next.js

demos/default/next.config.js

@@ -67,6 +67,11 @@ module.exports = {
         destination: '/',
         permanent: true,
       },
+      {
+        source: '/getStaticProps/4/',
+        destination: '/',
+        permanent: true,
+      },
     ]
   },
   // https://nextjs.org/docs/basic-features/image-optimization#domains

packages/runtime/src/helpers/redirects.ts

@@ -194,7 +194,7 @@ const generateStaticIsrRewrites = ({
 /**
  * Generate rewrites for all dynamic routes
  */
-const generateDynamicRewrites = ({
+export const generateDynamicRewrites = ({
   dynamicRoutes,
   prerenderedDynamicRoutes,
   middleware,
@@ -238,7 +238,11 @@ const generateDynamicRewrites = ({
             withData: true,
           }),
         )
-      } else if (prerenderedDynamicRoutes[route.page].fallback === false && !is404Isr) {
+      } else if (
+        prerenderedDynamicRoutes[route.page].fallback === false &&
+        !is404Isr &&
+        !process.env.LEGACY_FALLBACK_FALSE
+      ) {
         dynamicRewrites.push(...redirectsForNext404Route({ route: route.page, buildId, basePath, i18n }))
       } else {
         dynamicRewrites.push(