It may be a bit late, but if anyone else is interested in the answer to this... You can upgrade a software install of vTM from 8.0 to 17.4 but you can not do this directly with a virtual appliance (VA) . The reasons and method for upgrading are explained here:
https://community.pulsesecure.net/t5/Pulse-Secure-vADC/Upgrading-and-reinstalling-SteelApp-Traffic-Manager-Virtual/ta-p/32981
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