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
- Open browser Network tab (F12 > Network) and find the failing request — check the status code and response body
- For CORS errors: configure your API server to allow requests from your frontend domain
- For 401/403: check that your API key or auth token is being sent correctly in the request headers
- For 500: check server logs for the actual error — the frontend error won't have details
- For timeouts: check if the API endpoint is accessible from your deployment environment
Real developers can help you.
Describe what's wrong in plain English. No technical knowledge needed.
Get HelpFrequently 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.