Graceful upgrade from 7.0.12 to 7.2.6 or 7.2.7, or from 7.0.12 to 7.4.2 or 7.4.3 will fail on the FortiGate 6501F/6500F, FortiGate 7060E with slot6 occupied, and FortiGate 7121F with slot12 occupied.Workaround: Disable uninterruptible-upgrade before performing the firmware upgrade:config system ha set uninterruptible-upgrade disable endNote that traffic will be interrupted for 15 to 45 minutes, depending on the size of the configurations.