Flutter Web: /widget Redirect Issue on Vercel Subdomains

Help
1

Hi Vercel community,

I have a unique issue with a Flutter web app deployment where subdomain routing behaves differently than the main domain:

Current Behavior:

Working Configuration for Main Domain:

{
    "version": 2,
    "name": "myapp",
    "rewrites": [
      {
        "source": "/(.*)",
        "destination": "/index.html"
      }
    ]
}

Technical Setup:

  • Flutter web application
  • GoRouter for client-side routing
  • PathUrlStrategy enabled
  • Multiple attempted subdomain rewrite rules, none successful

What I’ve Tried:

  1. Different rewrite patterns including negative lookaheads
  2. Host-based conditions in rewrites
  3. Various combinations of source/destination paths

Project Structure:

├── app/
│   └── index.html
├── public/
├── support/
└── vercel.json

This seems to be a specific edge case with Flutter web’s routing system interacting with Vercel’s subdomain handling. Has anyone encountered this or found a solution?

Thanks in advance!

2

The domain troubleshooting guide can help with most custom domain configuration issues. You might be able to use that guide to solve it before a human is available to help you. Then you can come back here and share the answer for bonus points.

You can also use v0 to narrow down the possibilities.