I have a VCSA 6.5 install on an ESXi 6.5 host -- it's the only thing on this particular machine.  It's licensed with VMWare Essentials (not plus) because I don't need much.

The host machine needs to be retired before it fails and I have a new server ready, with ESXi 7 installed, no guests at the moment. 

At the same time, I have a license now for Essentials on 7.0 and would like to upgrade the VCSA to 7 and have it on the new machine. The VCSA installer makes it look like I can upgrade/migrate from the old VCSA to a new appliance on the new hardware, and in fact that is what I did in the upgrade from 5 to 6.5.

However, the tool is not able to get past checking the source VCenter installation. The logs indicate a bundle of errors in trying to get information from the source machine with the error of "Current license or ESXi version prohibits execution of the requested operation."

Is this because the Essentials license doesn't include some necessary feature for upgrade/migrate? What is the right way to solve this problem?