Your app works on your machine. You deploy to Vercel and get one of these: Error: supabaseUrl is required. AuthApiError: Invalid API key OpenAI API error: 401 Incorrect API key provided: undefined Or process.env.MY_KEY is simply undefined in production. Why it happens .env.local is not deployed (it's git-ignored, as it should be). Vercel needs its own copy. The variable was added after the last deployment. Env vars only apply to new deployments. It ...