InvalidOperationException, Collection was modified;

[Hårek]

My application works fine on the development PC, but it fails when I run it on the target PC.
The target runs XP (fully up to date), I have installed dotnetfx and Measurement Studio 8 (with the patch).
I use Visual C# 2005 Express.
I have used the Publish Wizard in Release configuration

When my application starts I get a messagebox saying there was an Unhandled exception, and two graphs in a window have red crosses on them. I can continue and the rest of the application works, including another window with graphs.

The exception dump:
************** Exception Text **************
System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
at System.Collections.Hashtable.HashtableEnumerator.MoveNext()
at UICM.ac.c(ComponentDrawArgsInternal )
at UICM.ac.DrawForeground(ComponentDrawArgsInternal args)
at NationalInstruments.Restricted.ControlElement.a(ComponentDrawArgsInternal , Rectangle , Boolean )
at NationalInstruments.Restricted.ControlElement.DrawChildren(ComponentDrawArgsInternal args, Rectangle clipRectangle)
at NationalInstruments.Restricted.ControlElement.a(ComponentDrawArgsInternal , Rectangle , Boolean )
at NationalInstruments.Restricted.ControlElement.DrawChildren(ComponentDrawArgsInternal args, Rectangle clipRectangle)
at NationalInstruments.Restricted.ControlElement.a(ComponentDrawArgsInternal , Rectangle , Boolean )
at NationalInstruments.Restricted.ControlElement.a(ComponentDrawArgsInternal , Rectangle )
at NationalInstruments.Restricted.ControlElement.Paint(PaintEventArgs e)
at NationalInstruments.UI.WindowsForms.ControlBase.OnPaint(PaintEventArgs e)
at System.Windows.Forms.Control.PaintWithErrorHandling(PaintEventArgs e, Int16 layer, Boolean disposeEventArgs)
at System.Windows.Forms.Control.WmPaint(Message& m)
at System.Windows.Forms.Control.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)

---------------------------
Could not include everything since message exceeds 5000 characters.

[Elton Wells]

From the description and the stack trace, I believe that the problem is that you are updating the graph from a non-UI thread. This is a problem because Windows Forms controls are not thread-safe. Notice that the class overviews of all .NET Framework and Measurement Studio Windows Forms controls have a thread safety section that states:

"Only the following members are safe for multithreaded operations: BeginInvoke, EndInvoke, Invoke, InvokeRequired, and CreateGraphics."

For more information, see the .NET Quickstart article "Making procedure calls across thread boundaries." Please check if this is the problem and post a reply with what you find. Thanks.

- Elton

[Hårek]

You are right. It works now. Thanks.

I have had a few 'reminders' about IllegalCrossThreadCalls during development, and fixed those with delegates.
I thought I had it sorted out, but it is easy to loose track of which task is doing what. And it was a bit unexpected to get that kind of exception.