Consecutive slashes in URL trigger routing error and no page renders in browser when Next.js runs behind gateway

[cosieLq]

Link to the code that reproduces this issue

https://github.com/cosieLq/exampleApp_nextjs/tree/reproduction-double-slash-routing-error

To Reproduce

1. Start the application (npm run dev or npm run start)
2. Start the gateway (node proxy.js)
3. Go to localhost:8000///about
4. Observe browser console and see 'Error: invariant: invalid relative URL, router received...'

Current vs. Expected behavior

I expected no error in browser console and the page to render correctly.

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 23.6.0: Wed Jul 31 20:48:52 PDT 2024; root:xnu-10063.141.1.700.5~1/RELEASE_ARM64_T6020
  Available memory (MB): 16384
  Available CPU cores: 12
Binaries:
  Node: 20.15.1
  npm: 10.7.0
  Yarn: 1.22.19
  pnpm: N/A
Relevant Packages:
  next: 15.0.0-canary.179 // Latest available version is detected (15.0.0-canary.179).
  eslint-config-next: N/A
  react: 19.0.0-beta-04b058868c-20240508
  react-dom: 19.0.0-beta-04b058868c-20240508
  typescript: 5.1.3
Next.js Config:
  output: N/A

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

Internationalization (i18n), Navigation, Pages Router

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

next dev (local), next start (local), Other (Deployed)

Additional context

When i18n is disabled in next.config.js, no error will appear and the page renders correctly.

[PreethiPantangi]

Hi @cosieLq

I've submitted a PR to address this issue as part of my first open source contribution. I would appreciate any feedback or suggestions you might have. Thank you!

PR - cosieLq/exampleApp_nextjs#1

[h0od]

I recently encountered this error as well.

The Chrome browser is giving the console error:
Uncaught SecurityError: Failed to execute 'replaceState' on 'History': A history state object with URL ...

While Firefox gives:
Uncaught DOMException: The operation is insecure

I can confirm that this is only happening if Next.js is accessed through a reverse proxy.

And I can also add that a trailing double-slash in the URL seems to work, but not somewhere else.

• https://some-domain.com/about// ✅
• https://some-domain.com//about ❌

[bgub]

I can reproduce this on Next.js 16.1.6 (Turbopack) with Pages Router.

Setup: a simple http-proxy gateway on port 8000 forwarding to Next.js dev server, with an /about page and i18n enabled (locales: ["en-US", "fr"]).

• http://localhost:8000///about/ with i18n enabled → Error: invariant: invalid relative URL, router received ///about/ — page does not render
• http://localhost:8000///about/ with i18n disabled → renders correctly, no error
• http://localhost:8000/about/ (normal URL) with i18n enabled → works fine

It seems like the i18n middleware is passing the un-normalized URL (with consecutive slashes) through to the client-side router, which then rejects it as an invalid relative URL. Without i18n, the URL gets normalized before reaching the router.

[iamsyh]

I'm having the same issue

Edit by maintainer bot: Comment was automatically minimized because it was considered unhelpful. (If you think this was by mistake, let us know). Please only comment if it adds context to the issue. If you want to express that you have the same problem, use the upvote 👍 on the issue description or subscribe to the issue for updates. Thanks!

[psytrxops]

I can reproduce this on Next.js 16.2.10 (Turbopack) with App Router and i18n middleware too.

Using Apache as HTTP Reverse Proxy.

ProxyPass / http://localhost:3000/
ProxyPassReverse / http://localhost:3000/

Fixed on prod using

# Collapse multiple root leading slashes to a single slash
# https://github.com/vercel/next.js/issues/70948
RewriteCond %{THE_REQUEST} \s//+([^\ ]*)
RewriteRule ^ /%1 [R=301,L]