Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on

Question

I get the following error

Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on.

This is a callback from a wcf.

I have a textBox and I need to update the value and appendtext to it. This value is coming back from another thread and updates the UI.

     public CarStatus CarState
    {
        get
        {
            return _carState;
        }
        set
        {
            _carState;= value;

            CarStatus tmpCarState;=null;
            if (txtResult.InvokeRequired)
            {
                txtResult.Invoke(new MethodInvoker(() => { tmpCarState;=null;= _carState;}));
            }
            txtResult.AppendText(string.Format("Car status is: {0}{1}", tmpCarState, Environment.NewLine));


        }

the following crashes!!

Answer 1

You forgot the else, as you're updating the text of the control via AppendText always, not just on non-invoke required.

And, well, I think you've got something wrong here: You're setting member variables through the invoker, but changing the actual WinForm component on any thread? You probably just want to but the whole block on Invoke.