InvalidOperationException: The calling thread cannot access this object because a different thread owns it. [duplicate]

Answer 1

You need to rejoin the main UI thread in order to affect the UI. You can check whether this is needed with InvokeRequired, and implement Invoke before referencing the controls.

private void calculate()
{
    if (InvokeRequired)
    {
        Invoke(new Action(() => calculate()));
    }
    else
    {
      //
    }
 }