I may be almost 79, but sometimes this old retired IT guy eventually gets things figured out. I finally resorted to doing a repair install by downloading the Win 10 ISO file and saving it to one of my internal SSHD drives (tried USB, but it failed), mounted
it (right click file - mount) and ran the installation app within Windows and chose to save everything (files & apps). It ran fine (takes some time even on this very fast computer) and when finished noticed that the ...6782 update had installed during the
repair install. When I checked for updates I noticed that the .net 3.5 (KB4569745) was ready to install as it did not install with the repair and for some reason Windows did not see it as already installed. Strange???? I then let it install which it did
without errors. Not sure why this worked, but it did as my computer now shows version 19041.450 as it should after installing ...6782 and everything seems to be fine and all my apps and other files are intact. Had a few minor tweaks to fix, but no big deal.
I have a feeling that the ...9745 did not install as it should and that caused the problem.
Now, since that worked, and I thought the problem might be the order the two updates were installed had something to do with it, I uninstalled ...9745 on my laptop, blocked that update using the Windows Show & Hide Utility that I use all of the time to delay
updates sometimes, rebooted and then tried to install ...6782 but it again got to 100% and then showed an error with the code 0x800f081f which again is the .net 3.5 error. I thought that would work but since it did not, I will run the repair install on the
laptop tomorrow as it is kind of late now and it is not near as fast as the desktop and will take a couple of hours. Since it worked on the desktop it should work on the laptop.
Not sure what happened, but something with these updates really screwed things up and the repair is the only way around it. I know it wasn't the .net preview I installed on 8/1 since I only installed it on the desktop and not the laptop. And, for me to
do the same wrong thing on both computers to cause the issue is very, very remote.
I guess the proof will be when the next cumulative arrives and if I can install it without problem. We will see!
Hope this helps!