# `client.canvas2d_context`: A canvas2d game has no 2D canvas

A build check error in the area "client/index.html rules". 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

The client is one page that talks to the room only through the kit (`Playable.connect`). It may load no other scripts or URLs, and it must render with the presentation mode the manifest names.

## How to fix it

A canvas2d game needs a canvas and a getContext("2d") call, or set presentationMode to the mode the game uses.

Load the kit's script and nothing else from outside, call `Playable.connect`, keep everything else inline or in client/assets, and never navigate the page.

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