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troubleshooting Question

BackgroundWorker is throwing Cross-thread exception

Avatar of tiwengr
tiwengr asked on
14 Comments1 Solution2501 ViewsLast Modified:
I am attempting to create a BackgroundWorker for a new application.  The purpose is to update the contents of a ListBox on Form1.  The updating is triggered by a Form Timer, timer1.  The timer interval is 5000.  So every 5 seconds, I would like the Background Worker to update the ListBox, listPending, by calling a public static method SRLib.loadPending() that probes a MySQL database looking for items needing approval.

I dragged a BackgroundWorker control onto Form1, called backgroundWorker1 and here's some code:

public Form1()

            backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);

            timer1.Enabled = true;

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
            SRLib.loadPending(listPending, "A", SRLib.userName); //loads all orders needing approval -

private void timer1_Tick(object sender, EventArgs e)

When this is run, I get the dialog saying "Problem encountered: System.InvalidOperationException:
Cross-thread operation not valid.  Control 'listPending' accessed from a thread other than the thread it was created on.

Then after that I get:
InvalidOperationException was unhandled:  This BackgroundWorker is currently busy and cannot run multiple tasks concurrently.

I have never created a BackgroundWorker before so I am probably making a bunch of rookie mistakes, but I would really appreciate some expert guidance here.

Avatar of p_davis

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