Fix Library ? Netlify
Netlify troubleshooting

Fix Netlify Environment Variables Undefined After Deploy

Netlify variables must be set in the correct context and exposed with the framework-specific public prefix when used in the browser.

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Common symptoms

  • Variable works locally but is undefined online.
  • Frontend API URL is blank after deploy.
  • Functions cannot read a secret.

What to check first

Platform: Netlify
Error: Environment variables undefined

Netlify variables must be set in the correct context and exposed with the framework-specific public prefix when used in the browser.

Step-by-step fix

  1. Add variables in Netlify Site configuration > Environment variables.
  2. Use VITE_ or NEXT_PUBLIC_ only for browser-safe values.
  3. Redeploy after changing build-time variables.
  4. Check branch deploy and production contexts separately.
VITE_API_URL=https://api.example.com
NEXT_PUBLIC_SITE_URL=https://example.com

Common mistake to avoid

Do not expose private tokens through public frontend prefixes.

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