FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
What is the 'Current FortiOS version' and 'Upgrade to FortiOS version': Make sure FortiGate is showing the firmware version that matches what was planned.
Make sure the proper upgrade path is followed if not recommended steps are:
Either can go back to the previous firmware version from Flash if it is only the last step in the firmware upgrade that has not followed the correct path, then follow the correct upgrade path: Steps of Downgrading the firmware after upgrade'.
Can the unit still power on? What is the LED status on the front panel? If there are no lights, and no console output, power cycle the FortiGate. If it still gets the same result then the unit is dead, open a TAC Ticket.
After power-cycling the unit, is there any console output? If yes, collect the logs and open a TAC Ticket.
Be sure that the right FortiOS image is selected for the correct platform. If not sure, open a TAC Ticket.
If there are issues uploading images to the device, ensure the TFTP server is running.
If the firmware upgrade does not load properly, or the unit does not show a login prompt after booting or continuously reboots, it is best to perform a fresh install of the firmware from a reboot using the CLI.
For units with BIOS version 50001000 or 6000100 (or newer) due to an enhanced BIOS-level signature and file integrity checking, the user cannot directly downgrade FortiOS to 6.0/6.2 or any other OS versions below v6.4.13/v7.0.12/v7.2.5/v7.4.0, a workaround will be needed, open a TAC Ticket for more information.
