Silent 500 Error on POST /api/auth/login - No Function Logs

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We use the Hobby version as we are trying out different providers for current deployments.

Deployment URL: https://wblareporting-backend-dev.vercel.app (Associated Frontend/Origin): https://wblareporting-dev.vercel.app

Problem: We are consistently receiving an HTTP 500 Internal Server Error response when sending a POST request to /api/auth/login on our development deployment (wblareporting-backend-dev.vercel.app).

Key Issue & Evidence: The primary issue is that despite the client receiving a 500 error, there are absolutely no logs generated in the Vercel Function Runtime Logs corresponding to the execution of the function handling this specific POST /api/auth/login request.

  • Extensive Logging Added: We have added detailed console.log statements throughout our Node.js/Express application:
    • At the very beginning of app.js using global middleware (position 0, before CORS and body-parser).
    • Inside specific middleware (express-validator) for the /api/auth/login route.
    • Inside the route handler in routes/authRoutes.js.
    • Inside the controller function (controllers/authController.js).
  • Logs Missing ONLY for Failing Request: While attempting login around Thursday, April 10, 2025, 12:30 PM EDT and 12:38 PM EDT (corresponding roughly to 16:30 UTC and 16:38 UTC), no logs related to POST /api/auth/login (e.g., @@@@ GLOBAL LOGGER START (POS 0): POST /api/auth/login @@@@) appeared in the Vercel Runtime Logs.
  • Logs Present for OTHER Requests: During the exact same timeframes, other requests to the same deployment were successfully processed and logged by the same global middleware. For example:
    • GET /api/health-check logged successfully around Apr 10 12:30:00 PM EDT (@@@@ GLOBAL LOGGER END (POS 0): GET /api/health-check - Status: 200...).
    • GET / logged successfully around Apr 10 12:38:40 PM EDT (@@@@ GLOBAL LOGGER END (POS 0): GET / - Status: 200...).
  • Valid Request Body: We have confirmed via browser developer tools that the request payload being sent is valid JSON (e.g., {"login": "user@example.com", "password": "PASSWORD_MASKED"}).
  • Minimal Handler Test: A previous test using a minimal handler directly in authRoutes.js for POST /api/auth/login (which just sent res.status(418).json(...)) did successfully execute and return the 418 response to the browser, proving the route can be reached by the function under simple conditions. However, restoring the full application logic reintroduced the silent 500 failure.

Conclusion: The evidence strongly suggests that the POST /api/auth/login request is encountering an error within the Vercel platform/infrastructure before our Node.js application code (app.js) is successfully invoked or allowed to log, despite the client receiving a 500 status code.

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It looks like the path /api/auth/login doesn’t exist in your project. The project returns {"status":"error","message":"Route not found","path":"/api/auth/login"}

I can confirm these 404 errors are in the runtime logs for your backend project with the @@@@ GLOBAL LOGGER START... details included. The frontend project does throw a 500 error, but that might not appear in the runtimes logs depending on how your project is handling the error.

Keep in mind that only 1 hour of logs are retained on the Hobby plan, so you need to check the logs fairly quickly after triggering the error.

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Thanks Amy! I was looking at the logs immediately afterwards and the particular larger 500 error wasn’t showing. I could see it in the DOM, which is why I said it was silent. But, after seeing you run or someone run I saw the error. I tried again, it didn’t show up immediately like the other runtimes did. I waited a few minutes and sure enough it popped up. That allowed us to track down the culprit, which was a database schema, which is what I thought, but couldn’t find where.

Just as an FYI, the path existed, it was in the auth section app.use('/api/auth', authRoutes); in app.js

You at least had us look again and realize that the runtime wasn’t instant, per sè.

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