Issue viewing preview on v0

v0
1

The preview is throwing me an error that says and shows this.

I’ve been having issues with this all morning. I have tried to duplicate the project into a new project.

This continually is breaking on my end, I also have run this command in the terminal and it not has resolved it.

pnpm install

CleanShot 2026-05-11 at 14.14.27@2x
CleanShot 2026-05-11 at 14.14.27@2x4064×2310 234 KB

CleanShot 2026-05-11 at 14.14.04@2x
CleanShot 2026-05-11 at 14.14.04@2x4080×2300 230 KB

2

Also, I’m seeing this as an issue when I visit the page.

502

Sandbox unreachable, restarting…

3

Also getting this as an error in the terminal

502: This sandbox is not listening on the requested port.Code: SANDBOX_NOT_LISTENINGID: iad1::mp7kj-1778524403602-f8fea3e21ed5

4

Hi Andrew,

The key error seems to be:

502: This sandbox is not listening on the requested port
Code: SANDBOX_NOT_LISTENING

That usually means the preview sandbox started, but the app inside it is not serving on the port v0 expects, or the dev server failed before it could bind to the port.

A few things I would check:

  1. Open the terminal/logs and look for the first error before the 502 message.

  2. Check package.json and make sure the dev script is normal for the framework, for example next dev.

  3. If this is a Next.js app, make sure the app is not hardcoding a different port.

  4. Avoid changing the dev server host/port unless v0 specifically requires it.

  5. If dependencies changed recently, delete/regenerate the lockfile or ask v0 to reinstall dependencies.

  6. Try a fresh duplicate only after confirming the original project’s dev command and dependency install are valid.

Running pnpm install may not fix this if the actual issue is that the dev server crashes or listens on the wrong port. The most useful detail to share would be the terminal output immediately before SANDBOX_NOT_LISTENING.