After upgrading one device in the HA group, the device is unable to become active and the dashboard reports the status as: suspended (Peer version too old). The device has been upgraded at least two minor feature releases away from the peer device in the HA group. When upgrading an HA group, each version upgrade has to be performed on both the devices in the HA group before upgrading to the next version.
Upgrade the peer to the last version this device was upgraded from, if downtime is permitted. Or, downgrade this device to the last version the device was upgraded from and upgrade the peer device to the same version before upgrading the pair to the intended version.