Created attachment 19362 [details]
After upgrading from Xamarin.Forms 2.3.3 to 188.8.131.52-pre1 I get the error:
...\Repro.KeyNotFound.App.xaml : error : The given key was not present in the dictionary.
In my main project I also get this error in two other xaml files.
As I don't know, what key it is missing I copied the whole app.xaml to the repro project.
I use XamlC in my solution and in the repro project. If I disable XamlC in the repro project, then it works. That project doesn't use all the styles I define in the app.xaml. My own solution crashes on start.
I tested on iOS and Android and both behave the same.
this will be fixed in 2.3.4-pre2