This may have been disgust already. Thought I'd share this finding from one of our consultants re v2016 installs:
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Wanted to give everyone a heads up on this if you have not run into this yet. If the prerequisite of .net 4.5 needs to be installed during the server install or client install, it will automatically reboot the computer/server. I am guessing this is for 2016 because I have not run into it before. This happened to me twice today. I thought maybe the first time was a fluke. Luckily I had everyone out of the system for the data copy. During the client install .Net was also needed and again it just forcefully shut down without allowing me to click OK to reboot.
So if .Net 4.5 pops up a prerequisite to be installed, you might want to get users off the server before clicking OK!