If you call the closeup() method on a additional button in a combo since the Microsoft updates KB3023222 KB3023224 this throws an exception:

An unhandled exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll

Additional information: Operation is not valid due to the current state of the object.

Removing the updates resolves the issue but of course leaves the end user open to the vulnerabilities the patch is supposed to fix.

This issues occurs in .net 4 / 4.5 / 4.5.1 with infragistics 14.1

To replicate add a combo to your form add a month calendar to your form.  Add a buttonright to your combo of type drop down and select the month calendar as the control.

Add an event on date selection to close the drop down and it will throw the error.

   private void monthCalendar1_DateChanged(object sender, DateRangeEventArgs e)
        {
            var btn = (Infragistics.Win.UltraWinEditors.DropDownEditorButton)ultraCombo1.ButtonsRight[0];
            btn.CloseUp();
        }

I have attached a sample project file that replicates the issue

But thew

private void monthCalendar1_DateChanged(object sender, DateRangeEventArgs e)

{

var btn = (Infragistics.Win.UltraWinEditors.DropDownEditorButton)ultraCombo1.ButtonsRight[0];

btn.CloseUp();

}