Failed .NET 3.5 Update Causes “Unhandled Exception” in Hyper-V Manager

I built a new Hyper-V server recently and for reasons I can no longer remember I added .NET 3.5 as a feature. I then ran WIndows Update which hung while installing a security update for .NET 3.5, (cursed .NET updates). I rebooted and that seemed to sort things out. That is until I tried to view the settings of one of my virtual machines in Hyper-V manager, where I was greeted by an “Unhandled exception” error. I didn’t take a screen shot or write the error down, however, in the error details it was moaning about JIT with some .NETTY looking syntax; so, I opened Windows Update and installed the outstanding .NET updates, rebooted and that fixed it.