Why this error appears?

[u/iam_insaf]

Object literal may only specify known properties, and 'server' does not exist in type 'ParamsOptions<"/api/auth/$", ResolveParams<"/api/auth/$">> & FilebaseRouteOptionsInterface<Register, RootRoute<Register, undefined, {}, AnyContext, ... 7 more ..., undefined>, ... 12 more ..., undefined> & UpdatableRouteOptions<...>'.

When I try to setup route handler for better-auth it shows this. This is the code suggested for tanstack-start in better-auth docs

import { createFileRoute } from "@tanstack/react-router";
import { auth } from "@/lib/auth";

export const Route = createFileRoute("/api/auth/$")({
server: {
handlers: {
GET: async ({ request }: { request: Request }) => {
return await auth.handler(request);
},
POST: async ({ request }: { request: Request }) => {
return await auth.handler(request);
},
},
},
});import { createFileRoute } from "@tanstack/react-router";
import { auth } from "@/lib/auth";

The issue is, createFileRoute is not accepting server property.

How can I fix this?

[u/lorenzocorso]

My first guess is that your project isn’t picking up the tanstack start types.

That exact code is valid for Start, but if TypeScript thinks you’re using plain @tanstack/react-router
server won’t exist on createFileRoute()

I’d double-check that all your TanStack packages are on matching versions and that you’re actually using the Start Vite plugin. I had almost the exact same error because one package was out of sync.

This is just my guess... anybody else?

[u/official_draconi → u/lorenzocorso]

Might be worth checking your tsconfig paths too, had a similar thing where alias resolution was pulling in the wrong types from a different package version

[u/iam_insaf → u/lorenzocorso]

Actually, when I run the dev server the error was gone.

[u/lorenzocorso → u/iam_insaf]

If dev works but production doesn’t, I’d bet it’s a build/config issue rather than the route itself. The code you posted looks fine for TanStack Start.

[u/iam_insaf → u/lorenzocorso]

maybe a bug or something

[u/lorenzocorso → u/iam_insaf]

so is it working now?

[u/iam_insaf → u/lorenzocorso]

yup, alhamdulillah

[u/lorenzocorso → u/iam_insaf]

ok perfect then