Updating is easy enough, however upon restarting Visual Studio I was finding Resharper was throwing exceptions on load and wanted to send information about them "home".
I decided to look at the "detailed information" that shows the stack trace and found the following:
Could not load file or assembly 'JetBrains.ReSharper.UnitTestFramework, Version=18.104.22.168
It turns out that this was happening in the xunit contrib plugin I had loading for Resharper so I could run my XUnit tests within its runner.
For now I rolled back by Resharper version until I get chance to either get the source for XUnit Contrib and fix the issue or someone else does it for me :)