Control 'progressBar1' accessed from a thread other than the thread it was created on in my business class [duplicate]

Answer 1

Your problem is that your control exists on thread A but you are trying to access it via thread B. This is a 'no-no'. Try the following code

private void btnSend_Click(object sender, EventArgs e)
{
    Task.Run(() => LoadData(System.Threading.SynchronizationContext.Current, progressBar1));
}

private void LoadData (System.Threading.SynchronizationContext synchContext, ProgressBar1ObjectType progressBar)
{
    string filePath = tbPath.Text;
    ETLBusiness etlBusiness = new ETLBusiness(filePath);

    synchContext.Post(state => etlBusiness.LoadData(progressBar), null);
}

Where 'ProgressBar1ObjectType' is the Type of progressBar1

Here is another option that may work better:

Thread _myThread = null;
private void btnSend_Click(object sender, EventArgs e)
{
    SynchronizationContext synchContext = SynchronizationContext.Current;
    _myThread = new Thread(() => LoadData(synchContext, progressBar1));

    myThread.Start();

}

private void LoadData (System.Threading.SynchronizationContext synchContext, ProgressBar1ObjectType progressBar)
{
    string filePath = tbPath.Text;
    ETLBusiness etlBusiness = new ETLBusiness(filePath);

    synchContext.Post(state => etlBusiness.LoadData(progressBar), null);
    _myThread.Abort();
}