This was one of the Compiler error that i received when trying to use the INotifyPropertyChanging in one of my sample Windows Phone F# project.
“INotifyPropertyChanging is not defined”
I was expecting that the INotifyPropertyChanging was included in the System Assembly but still had the same error.
You can solve the error INotifyPropertyChanging by including the mscorlib.Extensions.dll to your Windows Phone project.
Rebuild your Windows Phone solution and run the project 🙂