404 error using revalidate and useFetcher with v3_lazyRouteDiscovery

[ataias]

Reproduction

Calling revalidator.revalidate() as well as having a fetcher active trigger a "Not Found" error that does not seem catchable nor recoverable, even if the endpoint actually exists. You can see that happening in https://github.com/ataias/remix-use-fetcher-with-resource-route . Both dev mode and the production build suffer from the same issue.

System Info

System:
  OS: macOS 15.1.1
  CPU: (10) arm64 Apple M1 Pro
  Memory: 253.61 MB / 16.00 GB
  Shell: 3.7.1 - /opt/homebrew/bin/fish
Binaries:
  Node: 22.11.0 - /opt/homebrew/opt/node@22/bin/node
  npm: 10.9.0 - /opt/homebrew/opt/node@22/bin/npm
  pnpm: 8.6.9 - /opt/homebrew/bin/pnpm
  bun: 1.1.34 - /opt/homebrew/bin/bun
Browsers:
  Chrome: 131.0.6778.86
  Safari: 18.1.1
npmPackages:
  @remix-run/dev: 2.15.0 => 2.15.0 
  @remix-run/node: 2.15.0 => 2.15.0 
  @remix-run/react: 2.15.0 => 2.15.0 
  @remix-run/serve: 2.15.0 => 2.15.0 
  vite: ^5.1.0 => 5.4.11

Used Package Manager

npm

Expected Behavior

Opening the home page in repo https://github.com/ataias/remix-use-fetcher-with-resource-route should not hit the ErrorBoundary

Actual Behavior

Opening the home page in repo https://github.com/ataias/remix-use-fetcher-with-resource-route hits the error boundary with error No route matches URL "/en-br/api/hello-world-1?fetcher-1". However, the route exists.

[danielmoraes]

I can confirm that I am also experiencing this issue.

[joshbuddy]

I'm having a more flaky and tougher to reproduce issue which is when I have v3_lazyRouteDiscovery enabled I eventually get a 404 error from client-side routing. But I haven't nailed down a cause for this issue. I was hoping to find some sort of debug mode for the router to see what's going on inside there, but so far have been unable to find this option.

[nicksrandall]

I am also seeing something very similar to this issue. I have a fetcher that calls fetcher.load(...) in useEffect on mount to an API route (just a loader) and it frequently returns a 404 I'm guessing because that route hasn't been discovered yet?

I have confirmed that turning off v3_lazyRouteDiscovery completely removes the issue for me but It is preventing me from migrated to RRv7!

[Marcdj-02]

This seems like a critical bug. Using a fetcher, that is used to load data on mount (in a useEffect), always yields a 404 error if the route hasn't been discovered yet. Turning off the v3_lazyRouteDiscovery flag solves this issue for now. Seems quite similar to #10232.

[Marcdj-02]

I retract my statement that it is a critical bug.

So far, I have identified it as a race condition between the fetcher and a setSearchParams call (both on mount and when the v3_lazyRouteDiscovery is enabled). It seems that if the URL (searchparam) has changed between the fetcher invocation and return, it results in a 404 error. I am working on a reproduction repo and possibly a solution/PR for this. If anyone has more details or other similar cases, please let me know.

A workaround for this particular case would be to delay the setSearchParams a bit.

[nicksrandall]

I have added a reproduction of my issue to the react-router repo here: remix-run/react-router#13117

[github-actions]

Thank you for opening this issue, and our apologies we haven't gotten around to it yet!

With the release of React Router v7 we are sun-setting continued development/maintenance on Remix v2. If you have not already upgraded to React Router v7, we recommend you do so. We've tried to make the upgrade process as smooth as possible with our Future Flags. We are now in the process of cleaning up outdated issues and pull requests to improve the overall hygiene of our repositories.

We plan to continue to address 2 types of issues in Remix v2:

• Bugs that pose security concerns
• Bugs that prevent upgrading to React Router v7

If you believe this issue meets one of those criteria, please respond or create a new issue.

For all other issues, ongoing maintenance will be happening in React Router v7, so:

• If this is a bug, please reopen this issue in that repo with a new minimal reproduction against v7
• If this is a feature request, please open a new Proposal Discussion in React Router, and if it gets enough community support it can be considered for implementation

If you have any questions you can always reach out on Discord. Thanks again for providing feedback and helping us make our framework even better!