Static export with a specified basePath causes request mismatch for RSC payload .txt file

[yukiyokotani]

Link to the code that reproduces this issue

https://github.com/yukiyokotani/next-static-export-404-reproduce

To Reproduce

1. The code in the linked repository is deployed in the following github pages with static export.
   • https://yukiyokotani.github.io/next-static-export-404-reproduce/
2. This site only has a link to the root path: /. If you look at the network tab in the developer tools, you will see that the RSC Payload request corresponding to the root path is 404.

Current vs. Expected behavior

Current:

• A request for the RSC Payload corresponding to the root path is being made to https://yukiyokotani.github.io/next-static-export-404-reproduce.txt?_rsc=3eatq.

Expected:

• The request for the RSC Payload corresponding to the root path should be made to https://yukiyokotani.github.io/next-static-export-404-reproduce/index.txt?_rsc=3eatq. This is because the static export outputs the RSC payload .txt file as index.txt and not a file like next-static-export-404-reproduce.txt.

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 23.6.0: Mon Jul 29 21:16:46 PDT 2024; root:xnu-10063.141.2~1/RELEASE_ARM64_T8112
  Available memory (MB): 16384
  Available CPU cores: 8
Binaries:
  Node: 22.2.0
  npm: 10.8.1
  Yarn: 3.2.4
  pnpm: 9.4.0
Relevant Packages:
  next: 14.2.18 // An outdated version detected (latest is 15.0.3), upgrade is highly recommended!
  eslint-config-next: 14.2.18
  react: 18.3.1
  react-dom: 18.3.1
  typescript: 5.7.2
Next.js Config:
  output: export

Which area(s) are affected? (Select all that apply)

Output (export/standalone)

Which stage(s) are affected? (Select all that apply)

next build (local), Other (Deployed)

Additional context

In the code output generated by Static Export, the request path for the RSC Payload .txt files is constructed by appending .txt to the page path if the path ends with '/', and by appending index.txt otherwise. When basePath is set and trailingSlash is disabled (default settings), the root path '/' is treated as '', and according to the mentioned logic, the RSC Payload .txt file path becomes {basePath}.txt. However, the RSC Payload .txt file corresponding to '/' in the Static Export output is always index.txt. As a result, when trying to access {basePath}.txt, which should be {basePath}/index.txt, a 404 error occurs.

[Hartaithan]

there's no update on that? i'm experiencing that problem too.
next.js trying to load https://[URL]/[BASEPATH].txt?_rsc=1yfpv
instead of https://[URL]/[BASEPATH]/index.txt?_rsc=1yfpv

[kamyy]

Doesn't look like it's even merged into the canary release of 15.1 yet. Any ETA so I can at least test out the fix?

[mpn7]

Any news on this? I have a project ready for production and can't because of this bug.

[wojtekmaj]

We're also affected by this and we're currently evaluating the following patch:

diff --git a/dist/client/components/router-reducer/fetch-server-response.js b/dist/client/components/router-reducer/fetch-server-response.js
index 2d9c0421488770c601c1f119255fb88db9ebbe14..e2800a7e8d706d409f4033b4dfd2c77b29cafc53 100644
--- a/dist/client/components/router-reducer/fetch-server-response.js
+++ b/dist/client/components/router-reducer/fetch-server-response.js
@@ -58,7 +58,9 @@ async function fetchServerResponse(url, flightRouterState, nextUrl, currentBuild
         let fetchUrl = new URL(url);
         if (process.env.NODE_ENV === "production") {
             if (process.env.__NEXT_CONFIG_OUTPUT === "export") {
-                if (fetchUrl.pathname.endsWith("/")) {
+                if (fetchUrl.pathname === process.env.__NEXT_ROUTER_BASEPATH) {
+                    fetchUrl.pathname += "/index.txt";
+                } else if (fetchUrl.pathname.endsWith("/")) {
                     fetchUrl.pathname += "index.txt";
                 } else {
                     fetchUrl.pathname += ".txt";
diff --git a/dist/esm/client/components/router-reducer/fetch-server-response.js b/dist/esm/client/components/router-reducer/fetch-server-response.js
index 2e1e8a0bfd8cac4eaec839fedfe396c5a6ad2d56..8e190c55282d731b4e7da08cd00edcbe99a867cb 100644
--- a/dist/esm/client/components/router-reducer/fetch-server-response.js
+++ b/dist/esm/client/components/router-reducer/fetch-server-response.js
@@ -50,7 +50,9 @@ function doMpaNavigation(url) {
         let fetchUrl = new URL(url);
         if (process.env.NODE_ENV === "production") {
             if (process.env.__NEXT_CONFIG_OUTPUT === "export") {
-                if (fetchUrl.pathname.endsWith("/")) {
+                if (fetchUrl.pathname === process.env.__NEXT_ROUTER_BASEPATH) {
+                    fetchUrl.pathname += "/index.txt";
+                } else if (fetchUrl.pathname.endsWith("/")) {
                     fetchUrl.pathname += "index.txt";
                 } else {
                     fetchUrl.pathname += ".txt";

[vinodloha]

Not sure how long Next.js admins might take to fix it, I have handled this with a AWS Cloud Front function.

function handler(event) { var request = event.request; const url = request.uri; const parts = url.split('.txt'); // Handle .txt file requests for Next.js RSC if (parts.length > 1 && !url.startsWith('/index')) { request.uri = ${parts[0]}/index.txt${parts[1]}`;
}

//console.log(request.uri)

return request;

}`

[akshatsinha0]

Can we add a check for when 'url.pathname === process.env.__NEXT_ROUTER_BASEPATH'
to generate '/basePath/index.txt' instead of '/basePath.txt'
@mpn7