# Server.requireRunning()

- **Module:** Server
- **Package:** libtmux-swift
- **Language:** Swift
- **Kind:** method
- **Source:** https://github.com/libtmux/libtmux-swift/blob/f02a4668570e1cc5198c941413750e021f42c214/Sources/LibTmux/Navigation.swift#L277
- **Page:** https://libtmux.org/reference/swift/server-requirerunning()/

```
Server.requireRunning()() -> ()
```

Throws unless a server is listening.

Use this when only availability matters; reads such as ``sessions()``
already throw when tmux cannot answer.

## Raises

- `TmuxError`