# Actions must be used with server output.

> **ActionsWithoutServerOutputError**: A server is required to create callable backend functions. To deploy routes to a server, add an adapter to your Astro config and configure your route for on-demand rendering

## What went wrong?

[Section titled “What went wrong?”](#what-went-wrong)

Your project must have a server output to create backend functions with Actions.

**See Also:**

* [On-demand rendering](/en/guides/on-demand-rendering/)