vercel · ijjk · Mar 20, 2025 · Mar 18, 2025 · Mar 18, 2025 · Mar 19, 2025
diff --git a/packages/next/src/lib/load-custom-routes.test.ts b/packages/next/src/lib/load-custom-routes.test.ts
@@ -144,12 +144,25 @@ describe('loadCustomRoutes', () => {
 
       it('does not insert assetPrefix rewrite for /_next/ paths when assetPrefix is absolute URL', async () => {
         const customRoutes = await loadCustomRoutes({
-          assetPrefix: 'https://example.com/custom-asset-prefix',
+          assetPrefix: 'https://example.com',
         })
         expect(customRoutes.rewrites.beforeFiles).toEqual([])
         expect(customRoutes.rewrites.afterFiles).toEqual([])
       })
 
+      it('automatically insert assetPrefix rewrite for /_next/ paths when assetPrefix is absolute URL with a path', async () => {
+        const customRoutes = await loadCustomRoutes({
+          assetPrefix: 'https://example.com/custom-asset-prefix',
+        })
+        expect(customRoutes.rewrites.beforeFiles).toEqual([
+          {
+            destination: '/_next/:path+',
+            source: '/custom-asset-prefix/_next/:path+',
+          },
+        ])
+        expect(customRoutes.rewrites.afterFiles).toEqual([])
+      })
+
       it('does not add rewrite when assetPrefix === basePath', async () => {
         const customRoutes = await loadCustomRoutes({
           assetPrefix: '/base',

diff --git a/packages/next/src/lib/load-custom-routes.ts b/packages/next/src/lib/load-custom-routes.ts
@@ -596,19 +596,28 @@ async function loadRewrites(config: NextConfig) {
   // If assetPrefix is set, add a rewrite for `/${assetPrefix}/_next/*`
   // requests so that they are handled in any of dev, start, or deploy
   // automatically without the user having to configure this.
-  // If the assetPrefix is an absolute URL, we can't add an automatic rewrite.
+  // If the assetPrefix is an absolute URL, we still consider the path for automatic rewrite.
+  // but hostname routing must be handled by the user
   let maybeAssetPrefixRewrite: Rewrite[] = []
-  if (config.assetPrefix && !isFullStringUrl(config.assetPrefix)) {
-    const assetPrefix = config.assetPrefix.startsWith('/')
-      ? config.assetPrefix
-      : `/${config.assetPrefix}`
-    const basePath = config.basePath || ''
-    // If these are the same, then this would result in an infinite rewrite.
-    if (assetPrefix !== basePath) {
-      maybeAssetPrefixRewrite.push({
-        source: `${assetPrefix}/_next/:path+`,
-        destination: `${basePath}/_next/:path+`,
-      })
+  if (config.assetPrefix) {
+    let prefix = config.assetPrefix
+    if (
+      isFullStringUrl(config.assetPrefix) &&
+      URL.canParse(config.assetPrefix)
+    ) {
+      prefix = new URL(config.assetPrefix).pathname
+    }
+
+    if (prefix && prefix !== '/') {
+      const assetPrefix = prefix.startsWith('/') ? prefix : `/${prefix}`
+      const basePath = config.basePath || ''
+      // If these are the same, then this would result in an infinite rewrite.
+      if (assetPrefix !== basePath) {
+        maybeAssetPrefixRewrite.push({
+          source: `${assetPrefix}/_next/:path+`,
+          destination: `${basePath}/_next/:path+`,
+        })
+      }
     }
   }
 

diff --git a/test/e2e/app-dir/asset-prefix-absolute/app/layout.js b/test/e2e/app-dir/asset-prefix-absolute/app/layout.js
@@ -0,0 +1,10 @@
+export default function Root({ children }) {
+  return (
+    <html>
+      <head>
+        <title>Hello</title>
+      </head>
+      <body>{children}</body>
+    </html>
+  )
+}
diff --git a/test/e2e/app-dir/asset-prefix-absolute/app/page.js b/test/e2e/app-dir/asset-prefix-absolute/app/page.js
@@ -0,0 +1,3 @@
+export default function HomePage() {
+  return <p>Hello world</p>
+}
diff --git a/test/e2e/app-dir/asset-prefix-absolute/asset-prefix-absolute.test.ts b/test/e2e/app-dir/asset-prefix-absolute/asset-prefix-absolute.test.ts
@@ -0,0 +1,33 @@
+import { nextTestSetup } from 'e2e-utils'
+
+describe('app-dir absolute assetPrefix', () => {
+  const { next } = nextTestSetup({
+    files: __dirname,
+  })
+
+  it('bundles should return 200 on served assetPrefix', async () => {
+    const $ = await next.render$('/')
+
+    let bundles = []
+    for (const script of $('script').toArray()) {
+      const { src } = script.attribs
+      if (
+        src?.includes(
+          'https://example.vercel.sh/custom-asset-prefix/_next/static'
+        )
+      ) {
+        bundles.push(src)
+      }
+    }
+
+    expect(bundles.length).toBeGreaterThan(0)
+
+    for (const src of bundles) {
+      // Remove hostname to check if pathname is still used for serving the bundles
+      const bundlePathWithoutHost = decodeURI(new URL(src).pathname)
+      const { status } = await next.fetch(bundlePathWithoutHost)
+
+      expect(status).toBe(200)
+    }
+  })
+})
diff --git a/test/e2e/app-dir/asset-prefix-absolute/next.config.js b/test/e2e/app-dir/asset-prefix-absolute/next.config.js
@@ -0,0 +1,3 @@
+module.exports = {
+  assetPrefix: 'https://example.vercel.sh/custom-asset-prefix',
+}