Bug Report: Paraglide i18n Broken Since v1.141.2

Which project does this relate to?

Start

Describe the bug

Paraglide internationalization stopped working starting from TanStack Start v1.141.2
The issue also occurs when cloning the official example directly from this directory: https://github.com/TanStack/router/tree/main/examples/react/start-i18n-paraglide

Your Example Website or App

https://github.com/TanStack/router/tree/main/examples/react/start-i18n-paraglide

Steps to Reproduce the Bug or Issue

clone example: https://github.com/TanStack/router/tree/main/examples/react/start-i18n-paraglide
npm install
npm run dev

Expected behavior

Starting from v1.141.2: Dev server crashes "ERR_TOO_MANY_REDIRECT"

Screenshots or Videos

Platform

Router / Start Version: v1.141.2 - v1.141.3
OS: Debian
Browser: Brave, chrome, firefox

Additional context

Works on earlier versions of TanStack Start.
Regression begins at v1.141.2
Breakage also affects a freshly cloned example with no modifications.

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🔗 Similar Issues

Possible Duplicates

Bug Report: Paraglide i18n Broken Since v1.139.4 #5974

🔗 Related PRs

#5317 - fix: prevent HMR to throw error about entrypoints [merged]
#5344 - examples: fix paraglide start example [merged]
#5487 - examples: fix paraglide start link example [merged]
#5647 - test(solid-start): fix dev server for suspense transition [merged]
#5844 - docs(solid-router): i18n paraglide example [merged]

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This happens after build too with nitro.

When not using urlPatterns config and cookie strategy, it works only with baseLocale, otherwise many redirects too with any language.

I think this is related to #6072

Also seeing this issue. Seems like if the incoming request has an empty query param like ?utm_content=&utm_source=something then we get the infinite redirect.

Does not happen with local dev server or with local node js preview build.

It only fails with deployed nitro lambda build.

Removing the url strategy stop making the crash. but now I'm losing the language defined in the url first path segment when the cookie is missing

strategy: ["url", "cookie", "preferredLanguage", "baseLocale"],
// to ->
strategy: ["cookie", "preferredLanguage", "baseLocale"],

with url strategy, my error is

TypeError: Cannot read private member #state from an object whose class did not declare it
    at get referrer (node:internal/deps/undici/undici:10694:18)
    at Object.RequestInit (node:internal/deps/undici/undici:4568:35)
    at new Request (node:internal/deps/undici/undici:10404:34)
    at new Request$1 (file:///.../start-i18n-paraglide/node_modules/h3-v2/node_modules/srvx/dist/adapters/node.mjs:112:4)
    at paraglideMiddleware (/.../start-i18n-paraglide/src/paraglide/server.js:105:11)
    at async file:///.../start-i18n-paraglide/node_modules/@tanstack/start-plugin-core/dist/esm/dev-server-plugin/plugin.js:64:30

With these packages

  "@inlang/paraglide-js": "2.7.0",
  "@tanstack/react-router": "1.141.6",
  "@tanstack/react-start": "1.141.7",

Strategies
strategy: ["url", "cookie", "preferredLanguage", "baseLocale"]

Switching the server.ts to

import handler from "@tanstack/react-start/server-entry";
import { paraglideMiddleware } from "./paraglide/server";

export default {
  fetch(req: Request): Promise<Response> {
    return paraglideMiddleware(req, () => handler.fetch(req));
  },
};

Seems to fix the issue but may introduce other problems.

Paraglide JS maintainer here.

I ran PR #6072 through Codex with access to Paraglide's source code.

The most likely regression is in Paraglide’s server middleware
request cloning: it currently (pre-fix) constructs the “next”
request with new Request(url, request) (i.e. passing a Request
object as RequestInit). In runtimes that mix multiple Request
implementations (notably undici + h3/srvx/nitro wrappers),
undici will try to read private fields from that “init” object
and crash with errors like Cannot read private member #state… —
and depending on how the framework handles that failure, it can
surface as redirect loops / ERR_TOO_MANY_REDIRECT.

This is the line of code in the server middleware.

	? new Request(runtime.deLocalizeUrl(request.url), request)
		: // need to create a new request object because some metaframeworks (nextjs!) throw otherwise
			// https://github.com/opral/inlang-paraglide-js/issues/411
			new Request(request);

Given that new Request(input, options) is plain JS, undici should support it https://developer.mozilla.org/en-US/docs/Web/API/Request/Request.

Can someone try to add a try catch around the paraglide middleware/tanstack's server middleware to see if Codex assumption that ERR_TOO_MANY_REDIRECT is caused by an internal throw that isn't surfaced is true?

@samuelstroschein

@samuelstroschein

Both requests are of the same type but paraglide requests results to redirect to / which was already redirected to /en before, so it goes in a loop.

@MathieuDoyon How did you get your error?

Please Notice this my router.tsx

import { createRouter } from "@tanstack/react-router";
import { deLocalizeUrl, localizeUrl } from "./paraglide/runtime.js";
// Import the generated route tree
import { routeTree } from "./routeTree.gen";
// Create a new router instance
export const getRouter = () => {
  const router = createRouter({
    routeTree,
    scrollRestoration: true,
    defaultPreloadStaleTime: 0,
    rewrite: {
      input: ({ url }) => deLocalizeUrl(url),
      output: ({ url }) => localizeUrl(url),
    },
  });

  return router;
};

Original Incoming Request

{
  method: 'GET',
  url: 'http://localhost:3888/en/',
  headers: Headers {
    host: 'localhost:3888',
    connection: 'keep-alive',
    'cache-control': 'max-age=0',
    'sec-ch-ua': '"Not(A:Brand";v="8", "Chromium";v="144", "Microsoft Edge";v="144"',
    'sec-ch-ua-mobile': '?0',
    'sec-ch-ua-platform': '"Windows"',
    'upgrade-insecure-requests': '1',
    'user-agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Safari/537.36 Edg/144.0.0.0',
    accept: 'text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7',
    'sec-fetch-site': 'same-origin',
    'sec-fetch-mode': 'cors',
    'sec-fetch-dest': 'document',
    referer: 'http://localhost:3888/en/',
    'accept-encoding': 'gzip, deflate, br, zstd',
    'accept-language': 'en-US,en;q=0.9,en-GB;q=0.8',
    cookie: 'PARAGLIDE_LOCALE=en'
  },
  destination: '',
  referrer: 'about:client',
  referrerPolicy: '',
  mode: 'cors',
  credentials: 'same-origin',
  cache: 'default',
  redirect: 'follow',
  integrity: '',
  keepalive: false,
  isReloadNavigation: false,
  isHistoryNavigation: false,
  signal: AbortSignal { aborted: false 
}

Paraglide Request Result

{
method: 'GET',
url: 'http://localhost:3888/',
headers: Headers {
  host: 'localhost:3888',
  connection: 'keep-alive',
  'cache-control': 'max-age=0',
  'sec-ch-ua': '"Not(A:Brand";v="8", "Chromium";v="144", "Microsoft Edge";v="144"',
  'sec-ch-ua-mobile': '?0',
  'sec-ch-ua-platform': '"Windows"',
  'upgrade-insecure-requests': '1',
  'user-agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Safari/537.36 Edg/144.0.0.0',
  accept: 'text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7',
  'sec-fetch-site': 'same-origin',
  'sec-fetch-mode': 'cors',
  'sec-fetch-dest': 'document',
  referer: 'http://localhost:3888/en/',
  'accept-encoding': 'gzip, deflate, br, zstd',
  'accept-language': 'en-US,en;q=0.9,en-GB;q=0.8',
  cookie: 'PARAGLIDE_LOCALE=en'
},
destination: '',
referrer: 'about:client',
referrerPolicy: '',
mode: 'cors',
credentials: 'same-origin',
cache: 'default',
redirect: 'follow',
integrity: '',
keepalive: false,
isReloadNavigation: false,
isHistoryNavigation: false,
signal: AbortSignal { aborted: false }
}

This is the same behavior from Paraglide in both versions of Tanstack start.
In older versions the server handler.fetch didn't redirect so many redirects didn't occur

For what it's worth, I'm getting a similar error after updating to the latest versions of Tanstack Start and Router, and I'm not using Paragilde. For me it's the clerkMiddleware, when it calls new Request, undici throws. I can't even console.log the args.request in the clerkMiddleware function without undici complaining.

@DennisJosefsson

@DennisJosefsson I also hit this on the newest versions. I am also not using paraglide

@EthanShoeDev

@EthanShoeDev what are you using? also clerk?

I was able to reproduce my error by starting a new Tanstack Start project and adding this start.ts-file, with the start and router libraries set at 1.141.8. Another project with the same files, but with the very latest versions (1.142.7) instead, works. And from what I can see my main project also works after updating to 1.142.7.


const testMiddleWare = createMiddleware({ type: 'request' }).server(
  async (args) => {
    const request = new Request(args.request.url, {
      headers: args.request.headers,
      method: args.request.method,
      redirect: args.request.redirect,
      cache: args.request.cache,
      signal: args.request.signal,
    })

    console.log(request)

    return await args.next()
  },
)

export const startInstance = createStart(() => {
  return {
    requestMiddleware: [testMiddleWare],
  }
})

@schiller-manuel

Hi, I opened generaltranslation/paraglide-js#573 and submitted a defensive fix (generaltranslation/paraglide-js#574). The issue still exists in v1.145.3 - new Request(request) fails because undici can't access private #state fields from TanStack's custom Request wrapper. Is this expected to be fixed on the TanStack side? @schiller-manuel

@pi0

tanstack start does not wrap request. this must be coming from srvx
cc @pi0

@schiller-manuel

@schiller-manuel if you have upgraded srvx to 0.10 (it is a breaking change) please read notes to apply: https://github.com/h3js/srvx/releases/tag/v0.10.0

fix: address infinite redirect issue with latest tanstack start

deps: update @inlang/paraglide-js to v2.7.2 (#34)

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Bug Report: Paraglide i18n Broken Since v1.141.2 #6089

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Bug Report: Paraglide i18n Broken Since v1.141.2 #6089

Description

Which project does this relate to?

Describe the bug

Your Example Website or App

Steps to Reproduce the Bug or Issue

Expected behavior

Screenshots or Videos

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Additional context

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coderabbitai commented on Dec 13, 2025

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mustafa-barakat commented on Dec 13, 2025

EthanShoeDev commented on Dec 17, 2025

MathieuDoyon commented on Dec 18, 2025

mustafa-barakat commented on Dec 19, 2025

samuelstroschein commented on Dec 19, 2025

mustafa-barakat commented on Dec 20, 2025

DennisJosefsson commented on Dec 20, 2025

EthanShoeDev commented on Dec 20, 2025

schiller-manuel commented on Dec 21, 2025

DennisJosefsson commented on Dec 21, 2025

iktakahiro commented on Jan 4, 2026

schiller-manuel commented on Jan 4, 2026

pi0 commented on Jan 5, 2026

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