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Thread: ComboBox Items, Add, Remove, & Clear Generates an Error

  1. #1
    Join Date
    Aug 2004
    Location
    Orange, California
    Posts
    1,263

    Angry ComboBox Items, Add, Remove, & Clear Generates an Error

    I have a ComboBox on my form and I initially load it's list when the form is first opened. Once it becomes Active, anything that requires me to change the list generates the same error.

    I am using it for Disk Drives including removable USB Drives
    So these examples always fail:
    ComboBox1.Items.Add("G:")
    ComboBox1.Items.Remove("F:")
    ComboBox1.Items.Clear

    This is the Error Message:
    A first chance exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll

    I Can't Figure Out Why It Will Not Let Me Change The List???
    Last edited by Ron Weller; 04-11-2012 at 12:57 AM.

  2. #2
    Join Date
    Aug 2004
    Location
    Orange, California
    Posts
    1,263
    I have additional Information on this error.

    I used a (Try/Cath) block and this is the actual error message:
    Cross-thread operation not valid: Control 'DriveBox1' accessed from a thread other than the thread it was created on.

    Now I am trying to change the ComboBox List from an Event Handler
    You see I have a process that detects when a drive is added or removed.
    It is in a different thread; But all it does is raise an event when a drive is either added or removed.
    The Event Handler is part of the same Form as the ComboBox Control so there is no Cross-thread operation.

    Am I missing something here???
    Any Ideas would be helpful!

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