I was having trouble removing a computer from the Essentials 2012 R2 dashboard. Can’t recall the error but I do recall the entire dashboard crashing.
I found this thread on the dashboard crashing.
Which led to this TechNet article on uninstalling update KB3102467 to get rid of .NET 4.6.1. The article was written due to an incompatibility with Microsoft Exchange but includes general info on removing .NET 4.6.1. As of October 2016, this article says blocking .NET 4.6.1 is no longer needed. Not sure if that applies to the dashboard crashing issue or not.
Which led to KB3133990 about how to block future installation of .NET 4.6.1.
With .NET 4.6.1 removed and blocked, I was able to remove the computer.
Update 17 July 2018 See this post about blocking later versions of .NET.