Technical Tip: Migrate a FortiGate VM from VMware to Proxmox

Make sure that both the VMware and Proxmox VMs have the same number of interfaces and the same interface order.
Both KVM and ESXI FortiGates will assign ports in the order they are assigned to the VM. For example, the first interface will be port1, the second will be port2, etc. As long as the port mapping is in the same order in both VMware and Proxmox, it will align correctly and work fine.

1. Deploy the new VM on Proxmox, matching the same FortiOS version.
   
2. Perform a backup configuration of the VMware FortiGate VM. It will be necessary to edit the configuration header to match the new VM.

Example:

This is the configuration header for a VMware FortiGate:

For the KVM FortiGate to accept the configuration backup from the VMware FortiGate, 'FGVM64' needs to be replaced with 'FGVMK6'.

3. Shutdown the VMware VM. This is important because of the license, as there can only be a single VM connected to FortiGuard per license. Wait at least 90 minutes (6 - 24 hours is recommended in some cases) for FortiGuard servers to clear the old instance registration. This prevents 'Duplicate license detected' errors.
4. Restore the configuration on the Proxmox VM and upload the .lic file.

Details on troubleshooting KVM networking issues can be seen here: Troubleshooting Tip: Troubleshooting network issues when the FortiGate is hosted on a KVM hypervisor.

Note: Fortinet Technical Support (TAC) does not provide support for modifying configuration files that were initially from another FortiGate (for example, changing the interface names in the config file to match the newer FortiGate model), however parts of the configuration can be restored manually by copying the required configuration parts from the old backup configuration file to new configuration file (for example, address objects or some other settings).
It is recommended that the FortiConverter service be used for this task.

Related articles:

Technical Tip: FortiGate-VM License management, validation, and troubleshooting

Technical Tip: How to load/convert a FortiGate configuration file from one unit to another