When upgrading a FortiGate, follow the next steps:
1. Sign in to Fortinet's support site https://support.fortinet.com/Main.aspx
2. Go to the Download tab and then to images.
3. Select the correct product- Forti Gate/ Forti AP and so
4. Go to the path tab and put it the current version and the latest version
5. See what is the correct path and save it
6. when Signing in to the FrotiGate, there is an option to backup and upgrade according to the right path. make sure you take that option
7. save the backup and run the upgrade.
Rules:
(*) Always notify by email 12 hours prior to the upgrade to all companies that are using this product
(*) Always save the backup aside so you have a secure way to fix the situation if anything fails
(*) Always run the upgrade when there is no one in the office/ using the product
8. Run a timeless ping so you'll have the status of the upgrade right in front of you
9. If possible, upgrade physically and not from a VPN
10. If connected from a VPN, it'll crash as soon as you click the upgrade button. you can reconnect after 10-15 minutes. (depends on the number of versions path you have to do)
11. after reconnecting again, the Fortigates, due to their HA settings, will switch roles. FG1 would become the Secondary (Slave) and FG2 shall be the Primary- master. You can turn it around if you want, by restarting FG2. (during his restart, when FG2 is shut down, FG1 would take his Master place and become the primary)
12. If needed, also upgrade the APs too
13. Done!