I followed the directions from "/forums.unraid.net/topic/39381-upgrading-unraid-5-to-unraid-6/" to upgrade from V5. The wget option did not work due to a "connection error" when telneting into my unraid server with putty from windows. I then copied the "unRAIDServer.plg" into the config/plugins folder on the flash drive and rebooted multiple times. My system is still rev5. The system is an E4700 64-bit Intel processor and the thumb drive is a 4GB with only the UPS plugin other than the base install of unraid.
In the words of Marivn Gaye, What's goin' on? Are there updated links for within the update plugin?
BTW, I m finally upgrading my unraid from v5 after 15years or so because it is becoming increasingly more difficult to connect to it from my Win10 Pro machine which is used to rip Blurays and copy over to the NFS share.