# Patching and upgrading the SMC Appliance

To introduce improvements and enhancements for the current SMC Appliance version, install a hotfix patch. To upgrade the SMC Appliance, install an SMC Appliance upgrade patch.

Before upgrading, read the Release Notes.

It is important to upgrade the SMC Appliance before upgrading the engines. An old SMC version might not be able to recognize the new version engines and can generate an invalid configuration for them. The Management Server can control several older versions of engines. See the release notes for version-specific compatibility information.