https://vibefixkit.com/Free, plain-English fixes for the errors AI-built apps hit (env vars, CORS, Supabase RLS, hydration, deploys) with a copy-paste fix prompt for Cursor, Claude Code, Codex, Lovable, Bolt, Replit and v0, plus a library of starter prompts.https://vibefixkit.com/fix/hydration-mismatch/https://vibefixkit.com/fix/hydration-mismatch/The first render on the server and the first render in the browser produced different HTML.https://vibefixkit.com/fix/usestate-in-server-component/https://vibefixkit.com/fix/usestate-in-server-component/In the Next.js App Router, files are Server Components by default. Hooks and event handlers need a Client Component.https://vibefixkit.com/fix/next-public-env-undefined/https://vibefixkit.com/fix/next-public-env-undefined/Next.js only exposes env vars to browser code when their name starts with NEXT_PUBLIC_, and it inlines them at build time.https://vibefixkit.com/fix/env-works-locally-not-in-production/https://vibefixkit.com/fix/env-works-locally-not-in-production/.env files stay on your machine. Your host only knows the variables you add in its dashboard.https://vibefixkit.com/fix/vite-env-undefined/https://vibefixkit.com/fix/vite-env-undefined/Vite only exposes variables that start with VITE_ to client code, via import.meta.env, not process.env.https://vibefixkit.com/fix/secret-key-exposed-in-frontend/https://vibefixkit.com/fix/secret-key-exposed-in-frontend/Anything in client-side code, including NEXT_PUBLIC_ and VITE_ variables, is downloadable by anyone. Treat that key as compromised.https://vibefixkit.com/fix/cors-blocked/https://vibefixkit.com/fix/cors-blocked/The browser refused to give your page the response because the API didn't say your site is allowed to read it.https://vibefixkit.com/fix/supabase-rls-new-row-violates/https://vibefixkit.com/fix/supabase-rls-new-row-violates/Row Level Security is on for that table, but no policy allows this user to insert (or update) this row.https://vibefixkit.com/fix/supabase-select-returns-empty/https://vibefixkit.com/fix/supabase-select-returns-empty/RLS is filtering the rows out silently. A SELECT that no policy allows returns zero rows, not an error.https://vibefixkit.com/fix/supabase-invalid-api-key/https://vibefixkit.com/fix/supabase-invalid-api-key/The key your app sends doesn't match the project, or it's a legacy anon/service_role key that has been disabled.https://vibefixkit.com/fix/firebase-permission-denied/https://vibefixkit.com/fix/firebase-permission-denied/Your Firestore (or Storage / Realtime Database) security rules don't allow this read or write.https://vibefixkit.com/fix/firebase-unauthorized-domain/https://vibefixkit.com/fix/firebase-unauthorized-domain/Your deployed domain isn't in Firebase Authentication's authorized domains list.https://vibefixkit.com/fix/oauth-redirect-uri-mismatch/https://vibefixkit.com/fix/oauth-redirect-uri-mismatch/The callback URL your app sent isn't exactly one of the redirect URIs registered for that OAuth client.https://vibefixkit.com/fix/openai-429-rate-limit-quota/https://vibefixkit.com/fix/openai-429-rate-limit-quota/Either you're sending requests too fast, or the account has no credit left. Same status code, different fixes.https://vibefixkit.com/fix/llm-401-invalid-api-key/https://vibefixkit.com/fix/llm-401-invalid-api-key/The API received a key, but it's wrong, revoked, from another org/project, or mangled.https://vibefixkit.com/fix/npm-eresolve-dependency-tree/https://vibefixkit.com/fix/npm-eresolve-dependency-tree/Two packages want incompatible versions of a shared dependency (often React or Next.js), and npm refuses to guess.https://vibefixkit.com/fix/module-not-found-cant-resolve/https://vibefixkit.com/fix/module-not-found-cant-resolve/An import points at a file or package that isn't there, or a path alias the build doesn't know.https://vibefixkit.com/fix/case-sensitive-import-fails-on-deploy/https://vibefixkit.com/fix/case-sensitive-import-fails-on-deploy/macOS and Windows ignore letter case in file names. Linux build servers don't.https://vibefixkit.com/fix/tailwind-v4-postcss-plugin/https://vibefixkit.com/fix/tailwind-v4-postcss-plugin/Tailwind CSS v4 moved its PostCSS plugin into @tailwindcss/postcss, but your config still uses the v3 setup.https://vibefixkit.com/fix/tailwind-classes-not-applying/https://vibefixkit.com/fix/tailwind-classes-not-applying/Tailwind only generates CSS for complete class names it can find in your source files.https://vibefixkit.com/fix/eaddrinuse-port-in-use/https://vibefixkit.com/fix/eaddrinuse-port-in-use/Another process (often an old copy of your dev server) is already using that port.https://vibefixkit.com/fix/server-must-bind-0-0-0-0/https://vibefixkit.com/fix/server-must-bind-0-0-0-0/In containers and cloud hosts, your server must listen on 0.0.0.0 and on the port the platform gives you.https://vibefixkit.com/fix/spa-404-on-refresh/https://vibefixkit.com/fix/spa-404-on-refresh/Your single-page app handles routes in the browser, but the host looks for a real file at /dashboard and doesn't find one.https://vibefixkit.com/fix/stripe-webhook-signature/https://vibefixkit.com/fix/stripe-webhook-signature/Stripe signs the raw request body. Your code verified a parsed or modified body, or used the wrong signing secret.https://vibefixkit.com/fix/fetch-localhost-in-production/https://vibefixkit.com/fix/fetch-localhost-in-production/The deployed app still points at http://localhost, which on your user's device (or the server) is not your backend.https://vibefixkit.com/fix/mixed-content-blocked/https://vibefixkit.com/fix/mixed-content-blocked/Your HTTPS site tried to call an http:// URL, and the browser blocked it.https://vibefixkit.com/fix/cannot-read-properties-of-undefined/https://vibefixkit.com/fix/cannot-read-properties-of-undefined/Your code used a value before it existed, usually data that hasn't loaded yet or an API response with a different shape.https://vibefixkit.com/fix/objects-not-valid-as-react-child/https://vibefixkit.com/fix/objects-not-valid-as-react-child/JSX tried to render a whole object (or a Promise or Date) instead of a string, number, or element.https://vibefixkit.com/fix/too-many-re-renders/https://vibefixkit.com/fix/too-many-re-renders/A state update runs on every render, which causes another render, forever.https://vibefixkit.com/fix/err-require-esm/https://vibefixkit.com/fix/err-require-esm/CommonJS code (require) is loading a package that only ships ES modules (import).https://vibefixkit.com/fix/cannot-use-import-outside-module/https://vibefixkit.com/fix/cannot-use-import-outside-module/Node is treating your file as CommonJS, but it uses import/export syntax.https://vibefixkit.com/fix/vercel-function-timeout/https://vibefixkit.com/fix/vercel-function-timeout/Your serverless function ran longer than its maximum duration, which is common when waiting for a long LLM response.https://vibefixkit.com/fix/typescript-build-type-error/https://vibefixkit.com/fix/typescript-build-type-error/Dev mode is lenient about types; production builds run the type checker and stop on errors.https://vibefixkit.com/fix/github-push-protection-secret/https://vibefixkit.com/fix/github-push-protection-secret/GitHub found an API key or token in your commits and blocked the push. Good: it stopped a leak.https://vibefixkit.com/fix/node-engine-version-mismatch/https://vibefixkit.com/fix/node-engine-version-mismatch/Your host is building with an older (or different) Node.js than your packages need.https://vibefixkit.com/fix/ai-fix-loop/https://vibefixkit.com/fix/ai-fix-loop/Each blind retry adds more code and more guesses. Stop patching and get a diagnosis first.