C# WPF - MessageBox.Show() is called but no message is displayed on the screen

If your code is using MessageBox.Show, and using breakpoints you see that the function is executed but no message are shown on the Phone you migh try the following :

• Be sure using right click > show definition that it is pointing to the System.Windows.MessageBox version of the object
• That this is present in your usings list : using System.Windows;

If this is still not working, specially if boxes that previously working are not working anymore you might need to simply restart your Phone, this solved the issue for me.

I dont know the exact reason behind this thought.