I'm making it using MVVM.
I've been asking questions before and got a lot of answers. Among them, a binding error is output.
On the actual screen, it is bound without any problem.
However, an error is displayed in the output.
Please refer to my example. The situation is like this.
StartView => MainWindow Open -> Hierarchy1 Open
You click on UserControl A and UserControl B once at a time.
The binding is bound. However, you will get an output error while debugging.
Usercontrol A.xaml contains UserAGridView and UserATextBlock.
Usercontrol B.xaml contains ComboData, ComboDataItem, OnClickButtonCommand, and ButtonText.
Whenever you click on a Navigation Item, you will get a bounding error in the output about what is bound to that Usercontrol.
(Bind value in debugging screen works normally)
The same phenomenon appeared in the button in the Column in UsercontrolA, and I tried using a proxy, but it was the same.
What is the problem?