On Wed, 1 Nov 2017 17:56:48 -0400 "Jason" wrote in
article

I have tried this. No luck. So have the MS support people - they gathered
a ton of log files and will let me know what they find.

Another round with "support" and another failure. This time, they spotted
an error, 0x80007502, which they claim may require a complete re-
installation, a step I am -very- loath to take, given all I have on this
machine.

I did some searching on that error. One questionnable find suggested a
registry entry that I found (but haven't touched!) It's Group Policy
setting:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Win dows\WindowsUpdate\
DisableOSUpgrade REG_DWORD (1)

!

I am sufficiently ignorant of such things to dare change it, but it surely
aroused my suspicion. Searching for that particular entry online yielded a
number of articles, but none mentioned DisableOSUpgrade specifically, so I
left everything alone.