[▲ Vercel Community](/) · [Categories](/categories) · [Latest](/latest) · [Top](/top) · [Live](/live) [v0](/c/v0/59) # v0 preview environment missing Supabase environment variables 66 views · 1 like · 7 posts Jerry 2306 (@jerry-2306) · 2026-02-19 I started facing this as of yesterday. I started new chat with copying the `main` branch, which is also the code in production where things are working ok. I make a very very simple change in `v0` and I started getting this error: > **installHook.js:1 Supabase URL or Anon Key is missing. Returning null client.** Per the chat with `v0` it is the `v0` environment issue. I can grab the preview URL from `Vercel` and test there but the preview from `v0` fails. This is definitely a **v0 preview environment limitation**. The error shows that `process.env.NEXT_PUBLIC_SUPABASE_URL` and `process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY` are returning `undefined` in the browser. In `Next.js`, `NEXT_PUBLIC_*` environment variables are **replaced at build time** by the bundler (`Turbopack`/`Webpack`). They’re not actually read from `process.env` at runtime - `Next.js` injects the values during the build process. ## The Problem The `v0` preview was built before the environment variables were available in the system, so the build has `undefined` hardcoded where the env vars should be. ## Why this works in production When you deploy to `Vercel`, the build runs with the environment variables available, so they get properly injected into the bundle. ## Solutions 1. **This issue only affects v0 preview** - Your production deployment will work fine because `Vercel` builds with the env vars available. 2. **To test in v0, you can:** - Check your production/preview deployment on `Vercel` instead. - Wait for `v0` to auto-restart (happens periodically but can’t be manually triggered). Jerry 2306 (@jerry-2306) · 2026-02-19 Any feedback on this? Jerry 2306 (@jerry-2306) · 2026-02-19 now I have lost the ability to preview at all. This is big problem for in using v0. Please advise on what is going on  Pauline P. Narvas (@pawlean) · 2026-02-19 https://community.vercel.com/t/unable-to-login-supabase-is-not-configured-check-environment-variables/34056/4?u=pawlean Does this help? Pauline P. Narvas (@pawlean) · 2026-02-19 · ♥ 1 Re: preview, we're working on it! David Durham (@significantservices) · 2026-02-19 Why does this sort of thing happen so frequently on v0. The service is so inconsistent, seems like every other day. You guys implant some sort of bug? system (@system) · 2026-02-23 Hey! To help debug your v0 project, could you share your **v0 chat link**? It looks like `https://v0.app/chat/...` — you can copy it from your browser's address bar while in the chat. You'll also need to unlist the chat so our team can view it — here's how: https://v0.app/docs/sharing This helps the team reproduce what you're seeing much faster. Thanks!
