getEvent() throws "Context is not available" from a server function

[lorenjerickson]

Hello, everone. I have been chasing my tail trying to get something that should be very simple to work in @tanstack/start. The goal: read and write cookies from with in a server function. Short story is that I have a server function defined as follows:

export const login = createServerFn({
  method: "POST",
  response: "data",
})
  .validator((request: LoginRequest) => request)
  .handler(async (context) => {
    const event = getEvent();
    try {
      const data = await post<LoginResponse>({
        path: "/auth/login",
      });
      if (data.idToken && data.refreshToken) {
        setCookie(event,"access_token", data.idToken);
        setCookie(event, "refresh_token", data.refreshToken );
        return { success: true };
      }
      throw new Error("Invalid login response");
    } catch (error) {
      console.error("Login failed:", error);
      return { success: false, error: "Login failed" };
    }
  });

The post method above is just a wrapper around fetch that adds the Auhtorization header to requests that need it. These requests are going to an external API. This seems pretty consistent with examples I have seen elsewhere, but in this case the getEvent() call fails with the following stack trace:

Error: Context is not available
    at Object.use (file:///Users/loren/dev/lif3away-web/node_modules/unctx/dist/index.mjs:31:15)
    at getEvent (/Users/loren/dev/lif3away-web/node_modules/vinxi/runtime/http.js:338:32)
    at error (/Users/loren/dev/lif3away-web/apps/web/src/utils/api/auth.ts:21:19)
    at middlewareFn (/Users/loren/dev/lif3away-web/node_modules/@tanstack/start-client-core/src/createServerFn.ts:990:30)
    at applyMiddleware (/Users/loren/dev/lif3away-web/node_modules/@tanstack/start-client-core/src/createServerFn.ts:877:10)
    at next (/Users/loren/dev/lif3away-web/node_modules/@tanstack/start-client-core/src/createServerFn.ts:255:14)

Stepping through that stack trace seems to indicate that AsyncLocalStorage is not available, but I am not finding any information on why that would be, or how to fix it. Anyone else run into this?

Thanks in advance.

[sebasptsch]

Async storage is only available on newer node versions which may be the error.

[lorenjerickson]

Thanks for the tip. I was on node v20. I tried again with node v24.3.1, which has stable support for AsyncLocalStorage, but still get exactly the same result. Any other ideas?

[schiller-manuel]

can you provide a complete reproducer project?