NextJS API Endpoints returning Internal Server Error when deployed on IIS

Question

In local development, everything works as expected. Frontend calls the Nextjs API endpoints and receives the response with data.

However, when deployed to a IISNode, running on a Windows Server 2012 R2, API calls return only a Status Code 500 (Internal Server Error) response:

Content-Length: 21
Date: Thu, 01 Sep 2022 14:33:59 GMT
Keep-Alive: timeout=5
Server: Microsoft-IIS/8.5
X-Powered-By: ASP.NET

As a side note, I've tested with the same .env from production, so the connection string for the database is correct and working.

Some alterations I've tryied where:

1. Adding module.exports = {[webpackconfig], compress: false} to next.config.js
2. Setting NODE_OPTIONS='--http-server-default-timeout=0'

As a example of the code, on the frontend:

// frontend.tsx
const EscreverCartinha: NextPage = () => {
  const { data, isLoading, isError } = useCallMyImplementationSWR();
  return <ReactComponents example={data} />
}

// useCallMyImplementationSWR
const fetcher = async (url: string) => {
  const res = await fetch(url);
  if (!res.ok) {
    const { msg } = await res.json();
    const error = new Error(msg);
    throw error;
  }

  return res.json();
};

const useFetcher = (url: string) => {
  let { data, error } = useSWR(url, fetcher);

  return {
    data: data,
    isLoading: !error && !data,
    isError: error,
  };
};

export function useCallMyImplementationSWR() {
  const URL = `/api/endpoint`;

  return useFetcher(URL);
}

And, on pages/api/endpoint:

export default async function handler(
  _req: NextApiRequest,
  res: NextApiResponse
) {
  await prisma.example
    .findMany()
    .then(async (exampleparam) => {
      if (example == null) throw "No results found...";
      res.status(200).json(example);
    })
    .catch(async (error: any) => {
      console.error(error);
      res.status(500).json({ msg: error });
    });
}

Final note, on possible causes, the first request to any API endpoint in local development, using both next dev and next build && next start, are slow (max. 2~3s), but subsequent request are faster.

Answer 1

Try using failed request tracing to see details about 500 error.