Upgrading FortiGates in an HA cluster

You can upgrade the firmware on an HA cluster in the same way as on a standalone FortiGate. During a firmware upgrade, the cluster upgrades the primary unit and all of the subordinate units to the new firmware image.


Before upgrading a cluster, back up your configuration (Configuration backups), schedule a maintenance window, and make sure that you are using a supported upgrade path (https://docs.fortinet.com/upgrade-tool).

Uninterrupted upgrade

An uninterrupted upgrade occurs without interrupting communication in the cluster.

To upgrade the cluster firmware without interrupting communication, the following steps are followed. These steps are transparent to the user and the network, and might result in the cluster selecting a new primary unit.

  1. The administrator uploads a new firmware image using the GUI or CLI. See