Lovable Resend API Key Missing in Production
Quick Answer
The Resend API key was added locally but not in the deployed environment, or the backend function is trying to send mail from the browser instead of the server. Start with "Add the Resend key to the deployed environment" before making broader code changes.
You're in the right place if...
- !Emails work locally but not after deploy
- !The form submits, but no email is sent
- !Logs show missing RESEND_API_KEY or unauthorized email calls
Why this happens
The Resend API key was added locally but not in the deployed environment, or the backend function is trying to send mail from the browser instead of the server.
Fix
Add the Resend key to the deployed environment
Set RESEND_API_KEY in your deployment platform and redeploy so the server function picks it up.
Make sure email sending happens server-side
Use this prompt to move the mail call out of the frontend if needed.
Copy this prompt
Resend is failing because the API key is missing or being used in the wrong place. Please move the email send logic to a server-side route or function, read RESEND_API_KEY from server env vars, and return a clear error if the key is missing.
Redeploy and test with a real form submission
After adding the key, submit the form on the live site and confirm the email is sent end to end.
Prevent this next time
Treat every third-party API key as a deployment task. If it sends email, processes payments, or touches data, it belongs in server-side env vars before launch.
Frequently Asked Questions
No. The Resend API key must stay on the server.
Because local env files do not automatically carry over to Vercel, Railway, or other deployment environments.
Related fixes
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