I'm having this issue with a live app.

(Unfortunately this is post-mortem debugging - I only have this stack trace. I've never seen this personally, nor am I able to reproduce).

I get this Exception:

message=Cannot access a disposed object.
Object name: 'Button'.
exceptionMessage=Cannot access a disposed object.
Object name: 'Button'.
exceptionDetails=System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'Button'.
   at System.Windows.Forms.Control.CreateHandle()
   at System.Windows.Forms.Control.get_Handle()
   at System.Windows.Forms.Control.PointToScreen(Point p)
   at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ButtonBase.WndProc(Message& m)
   at System.Windows.Forms.Button.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
exceptionSource=System.Windows.Forms
exceptionTargetSite=Void CreateHandle()

It looks like a mouse event is arriving at a form after the form has been disposed.

Note there is none of my code in this stack trace.

The only weird (?) thing I'm doing, is that I do tend to Dispose() Forms quite aggressively when I use them with ShowModal() (see "Aside" below).

But I only do this after ShowModal() has returned (that should be safe right)?

I think I read that events might be queued up in the event queue, but I can't believe this would be the problem. I mean surely the framework must be tolerant to old messages? I can well imagine that under stress messages might back-log and surely the window might go away at any time?

Any ideas?

If you could even suggest ways of reproducing, that might be useful.

John

Aside:

TBH I've never quite understood whether calling Dispose() after Form.ShowDialog() is strictly necessary - the MSDN docs for ShowDialog() are to my mind a bit ambiguous.