diff --git a/packages/next/server/config.ts b/packages/next/server/config.ts
index 07406b6b32c0..94e9a7110a78 100644
--- a/packages/next/server/config.ts
+++ b/packages/next/server/config.ts
@@ -702,16 +702,6 @@ function assignDefaults(userConfig: { [key: string]: any }) {
     }
   }
 
-  if (result.experimental?.serverComponents) {
-    const pageExtensions: string[] = []
-    ;(result.pageExtensions || []).forEach((ext) => {
-      pageExtensions.push(ext)
-      pageExtensions.push(`server.${ext}`)
-      pageExtensions.push(`client.${ext}`)
-    })
-    result.pageExtensions = pageExtensions
-  }
-
   if (result.devIndicators?.buildActivityPosition) {
     const { buildActivityPosition } = result.devIndicators
     const allowedValues = [
diff --git a/test/e2e/app-dir/app-rendering/app/isr-multiple/layout.server.js b/test/e2e/app-dir/app-rendering/app/isr-multiple/layout.js
similarity index 100%
rename from test/e2e/app-dir/app-rendering/app/isr-multiple/layout.server.js
rename to test/e2e/app-dir/app-rendering/app/isr-multiple/layout.js
diff --git a/test/e2e/app-dir/app-rendering/app/isr-multiple/nested/page.server.js b/test/e2e/app-dir/app-rendering/app/isr-multiple/nested/page.js
similarity index 100%
rename from test/e2e/app-dir/app-rendering/app/isr-multiple/nested/page.server.js
rename to test/e2e/app-dir/app-rendering/app/isr-multiple/nested/page.js
diff --git a/test/e2e/app-dir/app-rendering/app/isr-ssr-combined/nested/layout.server.js b/test/e2e/app-dir/app-rendering/app/isr-ssr-combined/nested/layout.js
similarity index 100%
rename from test/e2e/app-dir/app-rendering/app/isr-ssr-combined/nested/layout.server.js
rename to test/e2e/app-dir/app-rendering/app/isr-ssr-combined/nested/layout.js
diff --git a/test/e2e/app-dir/app-rendering/app/isr-ssr-combined/nested/page.server.js b/test/e2e/app-dir/app-rendering/app/isr-ssr-combined/nested/page.js
similarity index 100%
rename from test/e2e/app-dir/app-rendering/app/isr-ssr-combined/nested/page.server.js
rename to test/e2e/app-dir/app-rendering/app/isr-ssr-combined/nested/page.js
diff --git a/test/e2e/app-dir/app-rendering/app/isr-ssr-combined/slow/layout.server.js b/test/e2e/app-dir/app-rendering/app/isr-ssr-combined/slow/layout.js
similarity index 100%
rename from test/e2e/app-dir/app-rendering/app/isr-ssr-combined/slow/layout.server.js
rename to test/e2e/app-dir/app-rendering/app/isr-ssr-combined/slow/layout.js
diff --git a/test/e2e/app-dir/app-rendering/app/isr-ssr-combined/slow/page.server.js b/test/e2e/app-dir/app-rendering/app/isr-ssr-combined/slow/page.js
similarity index 100%
rename from test/e2e/app-dir/app-rendering/app/isr-ssr-combined/slow/page.server.js
rename to test/e2e/app-dir/app-rendering/app/isr-ssr-combined/slow/page.js
diff --git a/test/e2e/app-dir/app-rendering/app/ssr-only/layout.server.js b/test/e2e/app-dir/app-rendering/app/ssr-only/layout.js
similarity index 100%
rename from test/e2e/app-dir/app-rendering/app/ssr-only/layout.server.js
rename to test/e2e/app-dir/app-rendering/app/ssr-only/layout.js
diff --git a/test/e2e/app-dir/app-rendering/app/ssr-only/nested/page.server.js b/test/e2e/app-dir/app-rendering/app/ssr-only/nested/page.js
similarity index 100%
rename from test/e2e/app-dir/app-rendering/app/ssr-only/nested/page.server.js
rename to test/e2e/app-dir/app-rendering/app/ssr-only/nested/page.js
diff --git a/test/e2e/app-dir/app-rendering/app/ssr-only/slow/layout.server.js b/test/e2e/app-dir/app-rendering/app/ssr-only/slow/layout.js
similarity index 100%
rename from test/e2e/app-dir/app-rendering/app/ssr-only/slow/layout.server.js
rename to test/e2e/app-dir/app-rendering/app/ssr-only/slow/layout.js
diff --git a/test/e2e/app-dir/app-rendering/app/ssr-only/slow/page.server.js b/test/e2e/app-dir/app-rendering/app/ssr-only/slow/page.js
similarity index 100%
rename from test/e2e/app-dir/app-rendering/app/ssr-only/slow/page.server.js
rename to test/e2e/app-dir/app-rendering/app/ssr-only/slow/page.js
diff --git a/test/e2e/app-dir/app-rendering/app/static-only/layout.server.js b/test/e2e/app-dir/app-rendering/app/static-only/layout.js
similarity index 100%
rename from test/e2e/app-dir/app-rendering/app/static-only/layout.server.js
rename to test/e2e/app-dir/app-rendering/app/static-only/layout.js
diff --git a/test/e2e/app-dir/app-rendering/app/static-only/nested/page.server.js b/test/e2e/app-dir/app-rendering/app/static-only/nested/page.js
similarity index 100%
rename from test/e2e/app-dir/app-rendering/app/static-only/nested/page.server.js
rename to test/e2e/app-dir/app-rendering/app/static-only/nested/page.js
diff --git a/test/e2e/app-dir/app-rendering/app/static-only/slow/layout.server.js b/test/e2e/app-dir/app-rendering/app/static-only/slow/layout.js
similarity index 100%
rename from test/e2e/app-dir/app-rendering/app/static-only/slow/layout.server.js
rename to test/e2e/app-dir/app-rendering/app/static-only/slow/layout.js
diff --git a/test/e2e/app-dir/app-rendering/app/static-only/slow/page.server.js b/test/e2e/app-dir/app-rendering/app/static-only/slow/page.js
similarity index 100%
rename from test/e2e/app-dir/app-rendering/app/static-only/slow/page.server.js
rename to test/e2e/app-dir/app-rendering/app/static-only/slow/page.js
diff --git a/test/e2e/app-dir/app-static/app/blog/[author]/[slug]/page.server.js b/test/e2e/app-dir/app-static/app/blog/[author]/[slug]/page.js
similarity index 100%
rename from test/e2e/app-dir/app-static/app/blog/[author]/[slug]/page.server.js
rename to test/e2e/app-dir/app-static/app/blog/[author]/[slug]/page.js
diff --git a/test/e2e/app-dir/app-static/app/blog/[author]/layout.server.js b/test/e2e/app-dir/app-static/app/blog/[author]/layout.js
similarity index 100%
rename from test/e2e/app-dir/app-static/app/blog/[author]/layout.server.js
rename to test/e2e/app-dir/app-static/app/blog/[author]/layout.js
diff --git a/test/e2e/app-dir/app-static/app/blog/[author]/page.server.js b/test/e2e/app-dir/app-static/app/blog/[author]/page.js
similarity index 100%
rename from test/e2e/app-dir/app-static/app/blog/[author]/page.server.js
rename to test/e2e/app-dir/app-static/app/blog/[author]/page.js
diff --git a/test/e2e/app-dir/app-static/app/layout.server.js b/test/e2e/app-dir/app-static/app/layout.js
similarity index 100%
rename from test/e2e/app-dir/app-static/app/layout.server.js
rename to test/e2e/app-dir/app-static/app/layout.js
diff --git a/test/e2e/app-dir/app-static/app/ssr-auto/loading.server.js b/test/e2e/app-dir/app-static/app/ssr-auto/loading.js
similarity index 100%
rename from test/e2e/app-dir/app-static/app/ssr-auto/loading.server.js
rename to test/e2e/app-dir/app-static/app/ssr-auto/loading.js
diff --git a/test/e2e/app-dir/app-static/app/ssr-auto/page.server.js b/test/e2e/app-dir/app-static/app/ssr-auto/page.js
similarity index 100%
rename from test/e2e/app-dir/app-static/app/ssr-auto/page.server.js
rename to test/e2e/app-dir/app-static/app/ssr-auto/page.js
diff --git a/test/e2e/app-dir/app-static/app/ssr-forced/loading.server.js b/test/e2e/app-dir/app-static/app/ssr-forced/loading.js
similarity index 100%
rename from test/e2e/app-dir/app-static/app/ssr-forced/loading.server.js
rename to test/e2e/app-dir/app-static/app/ssr-forced/loading.js
diff --git a/test/e2e/app-dir/app-static/app/ssr-forced/page.server.js b/test/e2e/app-dir/app-static/app/ssr-forced/page.js
similarity index 100%
rename from test/e2e/app-dir/app-static/app/ssr-forced/page.server.js
rename to test/e2e/app-dir/app-static/app/ssr-forced/page.js
diff --git a/test/e2e/app-dir/app-static/pages/.gitkeep b/test/e2e/app-dir/app-static/pages/.gitkeep
deleted file mode 100644
index e69de29bb2d1..000000000000
diff --git a/test/e2e/app-dir/app/app/(newroot)/dashboard/project/[projectId]/page.server.js b/test/e2e/app-dir/app/app/(newroot)/dashboard/project/[projectId]/page.js
similarity index 100%
rename from test/e2e/app-dir/app/app/(newroot)/dashboard/project/[projectId]/page.server.js
rename to test/e2e/app-dir/app/app/(newroot)/dashboard/project/[projectId]/page.js
diff --git a/test/e2e/app-dir/app/app/extension/page.server.js b/test/e2e/app-dir/app/app/extension/page.server.js
new file mode 100644
index 000000000000..6e4c13806737
--- /dev/null
+++ b/test/e2e/app-dir/app/app/extension/page.server.js
@@ -0,0 +1,3 @@
+export default function Page() {
+  return <h1 id="result-page">Result Page</h1>
+}
diff --git a/test/e2e/switchable-runtime/app/legacy-extension/page.server.js b/test/e2e/switchable-runtime/app/legacy-extension/page.server.js
new file mode 100644
index 000000000000..3fd783a5841a
--- /dev/null
+++ b/test/e2e/switchable-runtime/app/legacy-extension/page.server.js
@@ -0,0 +1,3 @@
+export default function Page() {
+  return <p>This file won't be treated as entry page file</p>
+}
diff --git a/test/e2e/switchable-runtime/app/node-rsc-isr/page.server.js b/test/e2e/switchable-runtime/app/node-rsc-isr/page.js
similarity index 100%
rename from test/e2e/switchable-runtime/app/node-rsc-isr/page.server.js
rename to test/e2e/switchable-runtime/app/node-rsc-isr/page.js
diff --git a/test/e2e/switchable-runtime/app/node-rsc-ssg/page.server.js b/test/e2e/switchable-runtime/app/node-rsc-ssg/page.js
similarity index 100%
rename from test/e2e/switchable-runtime/app/node-rsc-ssg/page.server.js
rename to test/e2e/switchable-runtime/app/node-rsc-ssg/page.js
diff --git a/test/e2e/switchable-runtime/app/node-rsc-ssr/page.server.js b/test/e2e/switchable-runtime/app/node-rsc-ssr/page.js
similarity index 100%
rename from test/e2e/switchable-runtime/app/node-rsc-ssr/page.server.js
rename to test/e2e/switchable-runtime/app/node-rsc-ssr/page.js
diff --git a/test/e2e/switchable-runtime/app/node-rsc/page.server.js b/test/e2e/switchable-runtime/app/node-rsc/page.js
similarity index 100%
rename from test/e2e/switchable-runtime/app/node-rsc/page.server.js
rename to test/e2e/switchable-runtime/app/node-rsc/page.js
diff --git a/test/e2e/switchable-runtime/index.test.ts b/test/e2e/switchable-runtime/index.test.ts
index 5485116ebc5c..077efe404696 100644
--- a/test/e2e/switchable-runtime/index.test.ts
+++ b/test/e2e/switchable-runtime/index.test.ts
@@ -161,6 +161,14 @@ describe('Switchable runtime', () => {
         )
       })
 
+      it('should not consume server.js file extension', async () => {
+        const { status } = await fetchViaHTTP(
+          context.appPort,
+          '/legacy-extension'
+        )
+        expect(status).toBe(404)
+      })
+
       it('should build /api/hello and /api/edge as an api route with edge runtime', async () => {
         let response = await fetchViaHTTP(context.appPort, '/api/hello')
         let text = await response.text()
@@ -216,7 +224,7 @@ describe('Switchable runtime', () => {
           export const config = {
             runtime: 'experimental-edge',
           }
-  
+
           export default () => new Response('edge response')
           `
         )
@@ -246,7 +254,7 @@ describe('Switchable runtime', () => {
           export const config = {
             runtime: 'experimental-edge',
           }
-  
+
           export default () => new Response('edge response again')
           `
         )
@@ -327,7 +335,7 @@ describe('Switchable runtime', () => {
           export const config = {
             runtime: 'experimental-edge',
           }
-  
+
           export default () => new Response('edge response')
           `
         )
@@ -360,7 +368,7 @@ describe('Switchable runtime', () => {
         export const config = {
           runtime: 'experimental-edge',
         }
-    
+
         export default  => new Response('edge response')
         `
         )
@@ -378,7 +386,7 @@ describe('Switchable runtime', () => {
           export const config = {
             runtime: 'experimental-edge',
           }
-          
+
         `
         )
         await check(
@@ -400,7 +408,7 @@ describe('Switchable runtime', () => {
           export default function Page() {
             return <p>Hello from page with invalid type</p>
           }
-          
+
           export const config = {
             runtime: 10,
           }
@@ -421,7 +429,7 @@ describe('Switchable runtime', () => {
             export default function Page() {
               return <p>Hello from page with invalid runtime</p>
             }
-            
+
             export const config = {
               runtime: "asd"
             }
@@ -442,11 +450,11 @@ describe('Switchable runtime', () => {
         export default function Page() {
           return <p>Hello from page without errors</p>
         }
-        
+
         export const config = {
           runtime: 'experimental-edge',
         }
-  
+
         `
         )
         await check(