IIS Information Manager Microsoft.Web.Configuration.AppHostFileProvider could no load file or assembly

If you have this error when clicking on a site or app pool in IIS manager, ensure you are launching the correct version!

Using Start menu search and clicking 7 by habit or not paying attention, rather than 10 as it should be for Windows 10…

This runs 7 from here:

Not 10 from here (right click .exe for version numbers):

Please comment if this helped you – I wish someone had blogged this before I made this mistake and had to scratch my head and going on a wild goose chase…