Check for known bugs that might affect your specific configuration before committing to the final version. If you'd like, I can: Help you find a modern replacement (like the Go to product viewer dialog for this item. Go to product viewer dialog for this item. ) based on your current throughput needs.
Perform a configuration backup before every single step in the upgrade chain. fortigate 200d latest firmware
Last practical use: A paperweight or a legacy training mule. Do not trust your network to EOL hardware running frozen firmware. Check for known bugs that might affect your