Had an interesting one the other day, deploying windows 2016 servers for a customer, setting one up as a jump server for support staff i naturally wanted to check that we could access the vSphere web console correctly using both flash and html variants.
By reading this post you can imagine that it didn’t work due to our old friend flash. However there is an easy fix
dism /online /add-package /packagepath:"C:\Windows\servicing\Packages\Adobe-Flash-For-Windows-Package~31bf3856ad364e35~amd64~~10.0.14393.0.mum"
Running this will get the respective flash component installed to enable you to use the web client again. More details are available at Technet Article