The 'Missing environment variables in .env file' error in Lovable means your app references environment variables that are not configured. In Lovable, secrets go in the Cloud tab under Secrets, not in .env files. Add your Supabase URL, anon key, and any API keys there. Variables must use the VITE_ prefix to be available in frontend code.
What does "Missing environment variables in .env file" mean in Lovable?
When Lovable shows this error, your application code references environment variables that are not set. Lovable uses Vite as its build system, which means client-side environment variables must be prefixed with VITE_ (e.g., VITE_SUPABASE_URL). Variables without this prefix are silently undefined on the client — no error, no warning, just undefined.
In Lovable's browser-based editor, you do not create .env files manually. Instead, environment variables are managed through the Cloud tab. Click the + button next to the Preview panel, then navigate to Secrets. This is where you add API keys, Supabase credentials, and any other sensitive configuration.
A critical detail specific to Lovable: .env files for Edge Functions must be placed under /supabase/functions/ (not /supabase/). Values copied from the Supabase production dashboard will not work because they are encrypted. This path-specific requirement catches many developers because it differs from standard Supabase documentation.
Common causes
Environment variables were not added
to the Cloud tab > Secrets section, which is the only place Lovable reads secrets
Client-side variables are missing the
required VITE_ prefix, making them silently undefined in the browser
The .env file for Edge Functions was placed in
the wrong directory (/supabase/ instead of /supabase/functions/)
Supabase integration was connected but
the auto-injected variables (VITE_SUPABASE_URL, VITE_SUPABASE_PUBLISHABLE_KEY) were not propagated
API keys were hardcoded in
the code during development and the code was later refactored to use environment variables without setting them
A Lovable project was duplicated or
forked, and secrets from the original project were not carried over to the copy
How to fix "Missing environment variables in .env file" in Lovable
Open your Lovable project. Click the + button next to the Preview panel to open the side panels. Navigate to the Cloud tab, then click Secrets. This is where all environment variables must be configured.
For Supabase integration, the essential variables are: VITE_SUPABASE_URL (your Supabase project URL), VITE_SUPABASE_PUBLISHABLE_KEY (the anon/public key), and VITE_SUPABASE_PROJECT_ID. These should be auto-injected when you connect Supabase through Lovable Cloud, but if you are using an external Supabase project, add them manually.
For third-party API keys (OpenAI, Stripe, SendGrid, etc.), add them in Secrets with descriptive names. Remember: VITE_ prefix means the variable is available in browser code. For secrets that should only be used in Edge Functions (like private API keys), do NOT use the VITE_ prefix — this prevents them from being exposed in the client bundle.
After adding secrets, you may need to refresh the preview or restart the build for the new variables to take effect. If your app was working before and suddenly shows this error, check if the Supabase connection was disrupted in the Cloud tab.
Never put API keys directly in your code files. Even in Lovable's managed environment, hardcoded keys can be exposed through the GitHub sync or if the project is shared.
// BAD: Hardcoded keys in codeconst supabase = createClient( 'https://abcdefgh.supabase.co', 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...');// BAD: Missing VITE_ prefixconst apiKey = import.meta.env.SUPABASE_URL; // undefined!// GOOD: Read from environment variables with VITE_ prefixconst supabaseUrl = import.meta.env.VITE_SUPABASE_URL;const supabaseKey = import.meta.env.VITE_SUPABASE_PUBLISHABLE_KEY;if (!supabaseUrl || !supabaseKey) { throw new Error( 'Missing Supabase environment variables. ' + 'Add them in Cloud tab → Secrets.' );}const supabase = createClient(supabaseUrl, supabaseKey);Prevention tips
- Always add environment variables through Lovable's Cloud tab > Secrets interface, not by creating .env files manually in the code editor
- Use the VITE_ prefix for client-side variables and no prefix for Edge Function-only secrets to prevent exposing private keys in the browser
- After adding or changing secrets, refresh the preview to ensure the new values are picked up by the Vite build process
- Add validation at the top of your main config file that checks for required environment variables and shows a clear error message if any are missing
Still stuck?
Copy one of these prompts to get a personalized, step-by-step explanation.
My Lovable app shows 'Missing environment variables in .env file'. I need to connect to Supabase and a third-party API. Where do I add environment variables in Lovable and what prefix do they need?
My Lovable project has a missing environment variables error. I need SUPABASE_URL, SUPABASE_KEY, and an OPENAI_API_KEY. Tell me exactly where to add each one in Lovable's interface and what prefix each needs.
Frequently asked questions
Where do I add environment variables in Lovable?
Click the + button next to the Preview panel, go to the Cloud tab, then click Secrets. This is the only place Lovable reads environment variables. Do not create .env files manually in the code editor.
Why does my Lovable app show "Missing environment variables in .env file"?
Your code references environment variables (like import.meta.env.VITE_SUPABASE_URL) that have not been configured in Lovable's Secrets panel. Add the required variables in Cloud tab > Secrets with the correct VITE_ prefix for client-side access.
Do I need the VITE_ prefix on all environment variables in Lovable?
Only for variables accessed in browser/client code. Variables used only in Supabase Edge Functions should NOT have the VITE_ prefix — this keeps them private and prevents them from being bundled into the client-side JavaScript.
Why are my Edge Function environment variables not working?
Edge Function .env files must be placed under /supabase/functions/, not /supabase/. Also, values copied from the Supabase production dashboard are encrypted and will not work. Use the raw, unencrypted values from your Supabase project settings.
Are environment variables preserved when I duplicate a Lovable project?
No. Secrets are not automatically carried over to duplicated or forked projects. After duplicating, you must re-add all environment variables in the new project's Cloud tab > Secrets.
Can RapidDev help configure environment variables for complex Lovable projects?
Yes. RapidDev can set up proper environment variable management, ensure secrets are correctly configured for both client-side and Edge Function usage, and implement validation to catch missing variables before they cause runtime errors.
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