WPF Getting Control null reference during InitializeComponent

Question

So my InitializeComponent method call in the Window\'s constructor is running through the XML and adding the controls and plugging them into their events.

Answer 1

I just had this issue too, and solved it by wrapping the line accessing the null control in a null check. This seems like a bit of a hack workaround.

I think WPF is trying to be helpful here by calling our Checked event during InitializeComponent(), in an effort to ensure that any UI logic (e.g. showing/hiding related components) is executed based on the initial state of the checkbox. I tested having the Checkbox unchecked by default, and the event handler is not called, even though I have it wired to both the Checked and Unchecked events. I even reproduced this in a blank WPF project with a single Checkbox on the screen, and it behaves the same.

The problem with this default behavior is obviously that some of the other components are not yet initialized. I think WPF should wait until all the components are initialized before firing the Checked event by default. This might not be considered a bug, but I'm gonna add a note to the relevant MSDN page anyway...