# `package.not_a_file`: A package file is a folder or a link

A build check error in the area "Package files". An error: the game cannot be published until it is fixed.

The build check runs on every game LobbyLab builds, and each problem it finds has a stable code, the exact message, the file and line when it names one, and a link to this page.

## What the check looks at

A game package is `manifest.json`, `server.ts` and `client/index.html`, with optional `client/assets/`. The check first makes sure these files exist, are plain files and fit their size limits (manifest 64 KB, server.ts 192 KB, index.html 512 KB).

## How to fix it

Keep exactly these files at the package root, as plain files (no links), within their limits.

See also: [every error code](/docs/errors), [the API reference](/docs/api) and [the docs](/docs).