UserControl Validating function is called even when AutoValidate is set to Disable on both the UC's design and the UC's instance

The main question is: do you want automatic validation?

◾ If you don't want automatic validation at form level:

• Set AutoValidate property of the Form to Disable and no Validating event will raise when you move between controls.
• Call ValidateChildren when you want to trigger validating events.

◾ If you want automatic validation at form level, but you don't want validation when clicking X button or a Cancel button:

• Set the AutoValidate property of the Form to EnableAllowFocusChange.

• For your Cancel button make sure you have set CausesValidation property to false.

• To prevent validating when closing the form, add the following code to your form:

   private const int WM_CLOSE = 0x0010;
   protected override void WndProc(ref Message m)
   {
       if (m.Msg == WM_CLOSE)
       {
           var autoValidate = this.AutoValidate;
           this.AutoValidate = AutoValidate.Disable;
           base.WndProc(ref m);
           this.AutoValidate = autoValidate;
       }
       else
           base.WndProc(ref m);
   }
  

  You may want to take a look at my post here for more details: How to prevent validating from being fired when I click X (Close button) on the form.

In my case the fix was:

7. Set the root of the main form to AutoValidate:Disabled. Merely setting this on the instance of the UC was not sufficient.