Thread operation not valid

I see the following in the output

A first chance exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll
System.Transactions Critical: 0 : <TraceRecord xmlns="http://schemas.microsoft.com/2004/10/E2ETraceEvent/TraceRecord" Severity="Critical"><TraceIdentifier>http://msdn.microsoft.com/TraceCodes/System/ActivityTracing/2004/07/Reliability/Exception/Unhandled</TraceIdentifier><Description>Unhandled exception</Description><AppDomain>PremiumCharger.vshost.exe</AppDomain><Exception><ExceptionType>System.InvalidOperationException, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</ExceptionType><Message>Cross-thread operation not valid: Control 'textboxRequest' accessed from a thread other than the thread it was created on.</Message><StackTrace> at System.Windows.Forms.Control.get_Handle()
at System.Windows.Forms.Control.set_WindowText(String value)
...........

Excerpts from my code:

class Form1
{
...
                    processor1.AfterProcessing += new Processor.AfterProcessingHandler(processor1_AfterProcessing);
...
       private void processor1_AfterProcessing(string request, string response)
        {
            textboxRequest.Text = request;
            textboxResponse.Text = response;
        }
...
}

class Processor
{
            backgroundWorker1 = new BackgroundWorker();
            backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
            backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
...
// Timer calls backgroundWorker1.DoWork()
...
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            OnAfterProcessing(stringRequest, stringResponse);
        }

        public delegate void AfterProcessingHandler(string request, string response);
        public event AfterProcessingHandler AfterProcessing;

        protected void OnAfterProcessing(string request, string response)
        {
            if (AfterProcessing != null)
            {
                if (request != null && response != null)
                {
                    AfterProcessing(request, response);
                }
            }
        }
...
}

Can anyone make heads or tails on this error and how to resolve it

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Thread operation not valid

big71
Invoke exists on the Control class, so you need the form or control instance.< xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

-mark

Program Manager

Microsoft

This post is provided "as-is"
ashish_2060
It looks like you are accessing a control on a non-UI thread. See the details of the exception: Cross-thread operation not valid: Control 'textboxRequest' accessed from a thread other than the thread it was created on.

You cannot do anything that affects the UI in the DoWork method.

< xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

-mark

Program Manager

Microsoft

This post is provided "as-is"
S&#246;nmez
Did you notice the error message ie
Cross-thread operation not valid: Control 'textboxRequest' accessed from a thread other than the thread it was created on.

private void processor1_AfterProcessing(string request, string response)
{
textboxRequest.Text = request;
textboxResponse.Text = response;
}

processor1_AfterProcessing is being called from a Thread which textboxRequest was not created on. You need to use Invoke( ) to Marshall the call to your Form1 class.

Look at
http://www.devsource.com/article2/0,1895,1893360,00.asp

This *will* fix your problem.

Wal
http200
DoWork doesn't call OnAfterProcessing, rather only backgroundWorker1.RunWorkerCompleted handler does.

I thought RunWorkerCompleted automatically mashalled to Form1.

Could it be because the background thread is called by the Timer thread But the timer1_Elapsed operates in the UI thread, right

Thanks for the quick responses. I'll add Invoke and report back.
Igor Tur
I can't figure out how to use Invoke. In the article, Invoke takes the form:

        void worker_DoWork(object sender, DoWorkEventArgs e)
        {
            for (int i = 0; i < (int)e.Argument; i++)
            {
                if (InvokeRequired)
                    Invoke(new Change(OnChange), i);
            }
        }

        private void OnChange(int i)
        {
            textBox1.Text += i.ToString() + ",";
            Application.DoEvents();
        }

        private delegate void Change(int i);

But, in mine, updating the DoWork event with

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
                if (InvokeRequired)
                    Invoke(new AfterProcessingHandler(OnAfterProcessing), stringRequest, stringResponse);
}

gives me an error "InvokeRequired does not exist in the current context."

Do I need to place InvokeRequired / Invoke in class Form1 If so, how do I invoke OnAfterProcessing which is in class Processor
Roil_O
The easiest way to find out re: marshalling is to ask.

private void processor1_AfterProcessing(string request, string response)
        {
            Console.WriteLine(this.InvokeRequired);
            //don't do the below if required, invoke
            textboxRequest.Text = request;
            textboxResponse.Text = response;
        }
giantpanda77
I was using System.Timers.Timer rather than System.Windows.Forms.Timer

Per http://msdn.microsoft.com/msdnmag/issues/04/02/TimersinNET/

"... the System.Timers.Timer class members are very similar to those of the System.Windows.Forms.Timer class. The biggest difference is that System.Timers.Timer is a wrapper around Win32 waitable timer objects and raises an Elapsed event on a worker thread rather than a Tick event on the UI thread."
Thread operation not valid

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