I have something to share on this finally.
I had a nice working version 30 and thought I should upgrade to version 39 to take advantage of the bugs fixes and enhancements.
Keep in mind that this is on a dev environment and I did not bother with backing up or restoring and of the cruft I had put together.
I started with copying over the contents of the 2.0.39 tar file to my C: drive (only one drive on my Windows 2016 VM). This yielded C:\PAW 2.0.39 with all the relevant folder and files as expected.
I ran the .\paw.ps1 stop from the services folder of the old version i.e. C:\PAW 2.0.30\services. Services seemed to stop.
Next I ran the .\Start.ps1 from C:\PAW 2.0.39 and entered Y to do the upgrade. After a while I entered Y to starting the Admin server.
Low and behold, the admin web page opened with my previous settings which I validated and updated.
I headed to the Services tab after the refresh and services seemed to be working.
I keyed in the URL for the PAW login and smiled as the page rendered and I could login.
I then thought I should go and run the clean script as my 120Gb drive now had about 5Gb free as I guessed at least two copied of the PAW VMs now resided in docker's windowsfilters folder. A good pruning would help.
Ran the clean.ps1 from the old C:\PAW 2.0.30 folder and it all went to pot! Various error messages relating to containers or images that could not be deleted. I tried again but to no avail. I had some disk space back but not enough.
Like all IT people would recommend, I went with a reboot and tried again, no luck. I figured I will live with it even though low on disk space.
I then fired up my Admintool for version 39 and noticed that for many services I now had duplicate entries and could no longer log in to PAW. This is where the panic really set in - my nice VM was a virtual paperweight.
So after toasting numerous VMs last year doing similar loads, IP changes etc. etc. I thought I would give things another go to try resolve.
My logic told me to try and roll back to a point where no services for either version existed and then load version 2.0.39 from scratch.
So my approach was probably a sledgehammer approach but without having enough technical knowledge this was the only tool in my belt.
First thing I did was to list all the Docker images PS> docker images -a
Without enough knowledge on how to script this, I painstakingly ran PS> docker rmi -f <image id>
Ok, so now the images were gone and I had to cleanup the Docker ProgramDat folder.
I stopped the Docker Service so that I could purge the ProgramData.
I downloaded
docker-ci-zap and ran PS>dcoker-ci-zap -folder C:\ProgramData\Docker
Once it completed the Docker folder was gone and my drive space was back.
I set about running .\Start.ps1 - settings were remembered as these reside in the C:\PAW 2.0.39 folders
After validation, the services (only one copy of each!) showed and were running!!
I could then log into PAW via the server's IP address.
What should have been a straight-forward upgrade seemed to have gone to hell. It is possible that I missed something but cannot see what as I followed the guidelines referenced earlier in this thread.
Would be happy to hear from anyone as to what I did wrong so that others can benefit from my misfortune.
I also hope the above will come in handy should anyone else suffer the same fate.
So Paul, as to whether or not the upgrade is simple, you decide. Good luck, you may need it!