How to upgrade FortiGate Firewall Firmware: Step-by-Step Guide to the Latest Version

Last updated: 19-12-2025

Introduction:

Keeping your FortiGate device's firmware up-to-date is critical for a secure and high-performing network. This guide simplifies the FortiOS upgrade process, ensuring a smooth and successful update.

Preparation:

  1. Upgrade Path: Follow the recommended upgrade path from Fortinet to avoid compatibility issues. Skipping versions is not recommended. (https://support.fortinet.com/download/firmwareimages.aspx)
  2. Download Firmware:
    • Visit the Fortinet support website.
    • Navigate to "Download" > "Firmware Images" and select "FortiGate".
    • Locate the appropriate firmware for your device model and download it using the HTTPS link.
  3. Verify Firmware Integrity: Use the provided method (likely checksum verification) to validate the downloaded file to ensure it hasn't been corrupted during download.
  4. Schedule Downtime: Minimize disruption by scheduling downtime for the upgrade process.
  5. Configuration Backup: Always create a recent backup of your configuration for a safe rollback option in case of unforeseen issues.
  6. Review Release Notes: Fortinet recommends reviewing the release notes for the specific firmware version before upgrading to understand any known issues or changes introduced.
  7. Maintenance Window: Schedule downtime to minimize service interruption during the upgrade.
  8. Console Access: Have console access available for troubleshooting if needed.

Upgrade Process:

1. Always upgrade using a locally stored copy of the firmware, not directly from the internet.
2. High Availability (HA) Devices: If your devices are in an HA configuration, refer to the specific upgrade procedures outlined in the Fortinet documentation.

  1. Copy Firmware: Transfer the downloaded firmware file to your management computer.
  2. Log in to Web GUI: Access the FortiGate web-based manager using your admin credentials.
  3. Navigate to Upgrade: Go to System > Dashboard > Status. Click "[Update]" next to the Firmware Version.
  4. Select Local File: Click "Browse" and locate the downloaded firmware image.
  5. Upgrade Confirmation: Confirm the upgrade by clicking "OK."

Post-Upgrade:

  • Automatic Reboot: The device will automatically reboot after the firmware installation is complete.
  • Version Check: Once rebooted, verify the new firmware version on your firewall to confirm a successful upgrade.

Rollback Plan (Limited):

  • Maintain a recent configuration backup for potential rollback scenarios.
  • Contact Fortinet's Technical Assistance Center (TAC) for troubleshooting assistance if necessary.
  • While downgrading firmware is not officially supported, a last resort option is to perform a flash format and reload the previous firmware and configuration (instructions in the Fortinet documentation). This should only be attempted with caution due to potential data loss.

Conclusion:

Upgrading your FortiOS is essential for optimal network security and performance. By following these steps and taking necessary precautions, you can ensure a smooth and successful upgrade process for your FortiGate device. Always consult the official Fortinet documentation for the latest information and specific upgrade procedures for your device model and configuration.