fix(start-server-functions-server): add base path to the RPC URL

[OnurGvnc]

Hi! This PR fixes a bug where server function urls are incorrect when the app uses a basePath.

The Problem:

The createServerRpc function (on the server) was creating URLs without the base path. However, the createClientRpc
function (on the client) was including it.

router/packages/start-server-functions-server/src/index.ts

Line 18 in b9f88c5

const url = `/${sanitizeBase(serverBase)}/${functionId}`

router/packages/start-server-functions-client/src/index.ts

Lines 9 to 12 in b9f88c5

	const sanitizedAppBase = sanitizeBase(process.env.TSS_APP_BASE || '/')
	const sanitizedServerBase = sanitizeBase(serverBase)
	const url = `${sanitizedAppBase ? `/${sanitizedAppBase}` : ``}/${sanitizedServerBase}/${functionId}`

For example, with a base path of '/app':

• Server URL: /_serverFn/<function_id>
• Client URL: /app/_serverFn/<function_id>

<form action={loginFn.url} method="POST">
hydration error:

  <LoginPage>
    <div>
      <h1>
        <form
+         action="/app/_serverFn/src_routes_auth_login_tsx--loginFn_createServerFn_handler"
-         action="/_serverFn/src_routes_auth_login_tsx--loginFn_createServerFn_handler"
           method="POST"
        >

This difference caused two main problems:

• A hydration error
• Broken forms, because submitting a form would go to the wrong URL (without the /app prefix).

The Solution:

I've updated createServerRpc to also use the base path when it creates the URL, just like the client version does.

File changed: packages/start-server-functions-server/src/index.ts

// Before
const url = `/${sanitizeBase(serverBase)}/${functionId}`

// After
const sanitizedAppBase = sanitizeBase(process.env.TSS_APP_BASE || '/')
const sanitizedServerBase = sanitizeBase(serverBase)

const url = `${sanitizedAppBase ? `/${sanitizedAppBase}` : ``}/${sanitizedServerBase}/${functionId}`

Now, both the client and server create the same correct URL.

[schiller-manuel]

thanks for this!
can you please add an e2e test for this in the e2e/react-start/custom-basepath project?

[OnurGvnc]

Thanks! I've added the e2e test.

Without this PR's changes, the test would fail with:

  Expected: "/custom/basepath/_serverFn/src_routes_logout_tsx--logoutFn_createServerFn_handler"
  Received: "/_serverFn/src_routes_logout_tsx--logoutFn_createServerFn_handler"

The test now passes with the PR's fix, confirming that server function URLs correctly include the app's basepath.

[nx-cloud]

View your CI Pipeline Execution ↗ for commit 61a7e61

Command	Status	Duration	Result
nx affected --targets=test:eslint,test:unit,tes...	✅ Succeeded	4m 30s	View ↗
nx run-many --target=build --exclude=examples/*...	✅ Succeeded	12s	View ↗

---

☁️ Nx Cloud last updated this comment at 2025-07-11 03:58:55 UTC

[pkg-pr-new]

More templates

• tanstack-router-react-example-authenticated-routes
• tanstack-router-react-example-authenticated-routes-firebase
• tanstack-router-react-example-basic
• tanstack-router-react-example-basic-default-search-params
• tanstack-router-react-example-basic-devtools-panel
• tanstack-router-react-example-basic-file-based
• tanstack-router-react-example-basic-non-nested-devtools
• tanstack-router-react-example-react-query
• tanstack-router-react-example-basic-react-query-file-based
• tanstack-router-react-example-basic-ssr-file-based
• tanstack-router-react-example-basic-ssr-streaming-file-based
• tanstack-router-react-example-basic-virtual-file-based
• tanstack-router-react-example-basic-virtual-inside-file-based
• tanstack-router-react-example-deferred-data
• tanstack-router-react-example-kitchen-sink
• tanstack-router-react-example-kitchen-sink-file-based
• tanstack-router-react-example-kitchen-sink-react-query
• tanstack-router-react-example-kitchen-sink-react-query-file-based
• tanstack-router-react-example-large-file-based
• tanstack-router-react-example-location-masking
• tanstack-router-react-example-navigation-blocking
• tanstack-router-react-example-quickstart
• tanstack-router-react-example-quickstart-esbuild-file-based
• tanstack-router-react-example-quickstart-file-based
• tanstack-router-react-example-quickstart-rspack-file-based
• tanstack-router-react-example-quickstart-webpack-file-based
• router-monorepo-react-query
• router-mono-simple
• router-mono-simple-lazy
• tanstack-router-react-example-scroll-restoration
• tanstack-search-validator-adapters
• tanstack-start-example-bare
• tanstack-start-example-basic
• tanstack-start-example-basic-auth
• tanstack-start-example-basic-react-query
• tanstack-start-example-basic-rsc
• tanstack-start-example-basic-static
• tanstack-start-example-clerk-basic
• tanstack-start-example-convex-trellaux
• tanstack-start-example-counter
• tanstack-start-example-large
• tanstack-start-example-material-ui
• tanstack-start-example-supabase-basic
• tanstack-start-tailwind-v4
• tanstack-start-example-trellaux
• tanstack-start-example-workos
• tanstack-router-react-example-view-transitions
• tanstack-router-react-example-with-framer-motion
• tanstack-router-react-example-with-trpc
• tanstack-router-react-example-with-trpc-react-query
• tanstack-router-solid-example-basic
• tanstack-router-solid-example-basic-devtools-panel
• tanstack-router-solid-example-basic-file-based
• tanstack-router-solid-example-basic-non-nested-devtools
• tanstack-router-solid-example-basic-solid-query
• tanstack-router-solid-example-basic-solid-query-file-based
• tanstack-router-solid-example-basic-ssr-streaming-file-based
• tanstack-router-solid-example-kitchen-sink-file-based
• tanstack-router-solid-example-quickstart-file-based
• tanstack-solid-start-example-bare
• tanstack-solid-start-example-basic
• tanstack-solid-start-example-basic-static

@tanstack/arktype-adapter

npm i https://pkg.pr.new/TanStack/router/@tanstack/arktype-adapter@4619

@tanstack/directive-functions-plugin

npm i https://pkg.pr.new/TanStack/router/@tanstack/directive-functions-plugin@4619

@tanstack/eslint-plugin-router

npm i https://pkg.pr.new/TanStack/router/@tanstack/eslint-plugin-router@4619

@tanstack/history

npm i https://pkg.pr.new/TanStack/router/@tanstack/history@4619

@tanstack/react-router

npm i https://pkg.pr.new/TanStack/router/@tanstack/react-router@4619

@tanstack/react-router-devtools

npm i https://pkg.pr.new/TanStack/router/@tanstack/react-router-devtools@4619

@tanstack/react-router-with-query

npm i https://pkg.pr.new/TanStack/router/@tanstack/react-router-with-query@4619

@tanstack/react-start

npm i https://pkg.pr.new/TanStack/router/@tanstack/react-start@4619

@tanstack/react-start-client

npm i https://pkg.pr.new/TanStack/router/@tanstack/react-start-client@4619

@tanstack/react-start-plugin

npm i https://pkg.pr.new/TanStack/router/@tanstack/react-start-plugin@4619

@tanstack/react-start-server

npm i https://pkg.pr.new/TanStack/router/@tanstack/react-start-server@4619

@tanstack/router-cli

npm i https://pkg.pr.new/TanStack/router/@tanstack/router-cli@4619

@tanstack/router-core

npm i https://pkg.pr.new/TanStack/router/@tanstack/router-core@4619

@tanstack/router-devtools

npm i https://pkg.pr.new/TanStack/router/@tanstack/router-devtools@4619

@tanstack/router-devtools-core

npm i https://pkg.pr.new/TanStack/router/@tanstack/router-devtools-core@4619

@tanstack/router-generator

npm i https://pkg.pr.new/TanStack/router/@tanstack/router-generator@4619

@tanstack/router-plugin

npm i https://pkg.pr.new/TanStack/router/@tanstack/router-plugin@4619

@tanstack/router-utils

npm i https://pkg.pr.new/TanStack/router/@tanstack/router-utils@4619

@tanstack/router-vite-plugin

npm i https://pkg.pr.new/TanStack/router/@tanstack/router-vite-plugin@4619

@tanstack/server-functions-plugin

npm i https://pkg.pr.new/TanStack/router/@tanstack/server-functions-plugin@4619

@tanstack/solid-router

npm i https://pkg.pr.new/TanStack/router/@tanstack/solid-router@4619

@tanstack/solid-router-devtools

npm i https://pkg.pr.new/TanStack/router/@tanstack/solid-router-devtools@4619

@tanstack/solid-start

npm i https://pkg.pr.new/TanStack/router/@tanstack/solid-start@4619

@tanstack/solid-start-client

npm i https://pkg.pr.new/TanStack/router/@tanstack/solid-start-client@4619

@tanstack/solid-start-plugin

npm i https://pkg.pr.new/TanStack/router/@tanstack/solid-start-plugin@4619

@tanstack/solid-start-server

npm i https://pkg.pr.new/TanStack/router/@tanstack/solid-start-server@4619

@tanstack/start-client-core

npm i https://pkg.pr.new/TanStack/router/@tanstack/start-client-core@4619

@tanstack/start-plugin-core

npm i https://pkg.pr.new/TanStack/router/@tanstack/start-plugin-core@4619

@tanstack/start-server-core

npm i https://pkg.pr.new/TanStack/router/@tanstack/start-server-core@4619

@tanstack/start-server-functions-client

npm i https://pkg.pr.new/TanStack/router/@tanstack/start-server-functions-client@4619

@tanstack/start-server-functions-fetcher

npm i https://pkg.pr.new/TanStack/router/@tanstack/start-server-functions-fetcher@4619

@tanstack/start-server-functions-server

npm i https://pkg.pr.new/TanStack/router/@tanstack/start-server-functions-server@4619

@tanstack/valibot-adapter

npm i https://pkg.pr.new/TanStack/router/@tanstack/valibot-adapter@4619

@tanstack/virtual-file-routes

npm i https://pkg.pr.new/TanStack/router/@tanstack/virtual-file-routes@4619

@tanstack/zod-adapter

npm i https://pkg.pr.new/TanStack/router/@tanstack/zod-adapter@4619

commit: 61a7e61