Xamarin.Forms - XamlCompilation MissingMethodException

This is most than probably a caching issue at the IDE or the project level.

If it's at IDE level: - do a clean - restart VS or XS - rebuild

but you probably tried that already.

My guess is that one of the nuget update didn't cleaned correctly, and you have different version of XF referenced on different project of your solution, or one .csproj file references the old .targets file.

Some manual housecleaning will solve the issue, hopefully.

If your project depends on a 3rd party assembly that uses XamlC, and if that assembly has been build on XF<2.3.3, you still can get this issue.

A fix exists and will be released as part of the first service release for XF 2.3.3