A Rolling Upgrade orchestrates the upgrade in an order that is meant to preserve cluster operation and minimize service impact during upgrade. This process has more stringent prerequisites (particularly regarding cluster high availability configuration) and can take longer to complete than an Express Upgrade.

	Note
	Rolling Upgrade is not supported for NiFi. During the Rolling Upgrade, each NiFi instance is stopped, upgraded, and restarted.

An Express Upgrade orchestrates the upgrade in an order that incurs cluster downtime but has less stringent prerequisites.