# PHP Version

In some cases an Altis version may provide support for multiple versions of PHP. This can be useful for testing and developing while updating an application to work on the latest available version of PHP.

To change the PHP version use the Local Server module configuration to set the `php` property:

```json
{
	"extra": {
		"altis": {
			"modules": {
				"local-server": {
					"php": "7.4"
				}
			}
		}
	}
}
```

Altis will always default to the _highest_ supported version of PHP unless support is marked as experimental. [See the PHP compatiblity chart here](docs://guides/updating-php/README.md) to see which version of PHP your version of Local Server will be running on by default, and which other versions are available.

## Restarting the environment

After changing the PHP version in composer.json, restart the environment with the following:

```
composer server stop && composer server start
```
