"Can’t download firmware from Fortinet—contract expired." Fix: Fortinet Support will often provide the last EOL build for free if you open a ticket citing "Security remediation for legacy hardware." It is not guaranteed, but it is worth a try.
If you cannot legally obtain the 5.4.13 firmware because your support contract expired a decade ago, you have two options: Fortigate 100d Firmware Download BEST
Official firmware must be obtained through the Fortinet Support Portal . 1. Verification & Pathing "Can’t download firmware from Fortinet—contract expired
However, the best business decision is to with a FortiGate 40F, 60F, or 70F. The 100D is a security liability, regardless of firmware version. Verification & Pathing However, the best business decision
As a legacy "D-series" device, it is considered End-of-Life (EOL) and no longer receives the latest security database updates for active inspection. 📥 How to Download & Install