I was just minding my own business, trying to install and configure the GP 2016 Web Client on a fresh Server 2012 R2 VM.
When I connected to the new VM, I saw this message.
"We couldn't complete the updates. Undoing changes."
The machine just sat there and didn't appear to do anything. It was stuck.
After finding a few useless suggestions relating to the same problem but for Windows 8, I finally found a reference to this TechNet thread.
Unfortunately, the suggestion to turn off Secure Boot on the VM didn't help. The thread discusses other workarounds, but I didn't know how to install BitLocker on a VM that wouldn't boot.
So then I saw the link to this post:
And it is there that I learned that using Server Manager, you can install roles or features onto a VM just by pointing to the VHD!!!
I followed the instructions, and it appears to have resolved the issue. The VM actually booted up and started applying the updates.
The update message started at 30%, and is now sitting at 100%. Unfortunately it's now just sitting at 100% and it has been several minutes, so I may have more than one problem to push through.
UPDATE: I let it sit at 100% for several minutes, but couldn't tell if it was doing anything or stuck again. So I turned it off, then turned the Secure Boot off again, then restarted. It then showed the "Undoing changes" again, but after a few minutes, it said "Preparing Windows" and actually finished booting.
Unfortunately, after it finally booted up, this was still showing in Windows Update. Ugh. Only 205 more to go.