Common Issues general

API Calls Failing With Errors in My AI App

Your app makes calls to an API (its own backend, Supabase, or a third-party service) and those calls fail. You see errors in the console like 500, 403, 404, or CORS errors.

Error Messages You Might See

CORS policy: No 'Access-Control-Allow-Origin' header 500 Internal Server Error 403 Forbidden 401 Unauthorized net::ERR_CONNECTION_REFUSED Timeout: request took too long

Common Causes

  • CORS not configured — browser blocks requests from your domain to the API
  • API key or auth token expired, missing, or wrong
  • API endpoint URL is wrong (still pointing to localhost or old URL)
  • Rate limiting — too many requests in a short time
  • Backend server error (500) due to unhandled exceptions

How to Fix It

  1. Open browser Network tab (F12 > Network) and find the failing request — check the status code and response body
  2. For CORS errors: configure your API server to allow requests from your frontend domain
  3. For 401/403: check that your API key or auth token is being sent correctly in the request headers
  4. For 500: check server logs for the actual error — the frontend error won't have details
  5. For timeouts: check if the API endpoint is accessible from your deployment environment

Real developers can help you.

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Frequently Asked Questions

What does a CORS error mean?

CORS (Cross-Origin Resource Sharing) is a browser security feature. It means your frontend (e.g., on Vercel) is trying to call an API on a different domain, and that API hasn't been configured to allow it.

I get a 500 error but don't know what's wrong. How do I find out?

A 500 error means the server crashed. The actual error is in the server logs, not in the browser. Check your hosting platform's logs.

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