I tried upgrading my company's project to Next 15, but every page just loads forever when calling next dev regardless of the --turbopack flag or not.

When I tried debugging why, I found that when an async function getI18nOnServer() that we have gets called and awaited on from any server component, it seems to successfully invoke the function; but when it returns, the page component appears to start over again from the start instead of continuing onwards.

The function looks like this:

import { headers } from "next/headers";
import {
  localeHeaderKey,
  pathnameHeaderKey,
  searchHeaderKey,
} from "~/injected-headers";
import { baseLocale, i18n } from "~/typesafe-i18n/gen-util";
import { loadLocale } from "~/typesafe-i18n/gen-util.sync";
import { localeSchema } from "~/utils/i18n/locale";
import "server-only";

export async function getLocaleFromHeaderOnServer() {
  // https://github.com/vercel/next.js/discussions/43179
  // we get this from a header so that we can get the locale from anywhere
  // serverside
  const requestHeaders = await headers();
  return localeSchema
    .catch(baseLocale)
    .default(baseLocale)
    .parse(requestHeaders.get(localeHeaderKey));
}

/**
 * @returns The translation functions for the locale that was detected from the
 * header
 */
export async function getI18nOnServer() {
  const locale = await getLocaleFromHeaderOnServer();
  loadLocale(locale);
  return i18n()[locale];
}

And the i18n functions are generated by this library: https://github.com/ivanhofer/typesafe-i18n

The rerurn value is something like: { some_i18n_key: () => string } ; it's a fairly big set of functions that gets returned.

I determined this by added console logs, and confirmed that the function does get called and concludes; but even after that function returns, the page component doesn't continue and appears to start over. If I remove the call to this function, then it proceeds properly.

Any ideas? Thanks! Would love to upgrade to Next 15.