The calling thread cannot access this object because a different thread owns it.WPF
Solution 1
Use Dispatcher.Invoke Method.
Executes the specified delegate synchronously on the thread the Dispatcher is associated with.
Also
In WPF, only the thread that created a DispatcherObject may access that object. For example, a background thread that is spun off from the main UI thread cannot update the contents of a Button that was created on the UI thread. In order for the background thread to access the Content property of the Button, the background thread must delegate the work to the Dispatcher associated with the UI thread. This is accomplished by using either Invoke or BeginInvoke. Invoke is synchronous and BeginInvoke is asynchronous. The operation is added to the event queue of the Dispatcher at the specified DispatcherPriority.
You are getting the error because your label is created on UI thread and you are trying to modify its content via another thread. This is where you would require Dispatcher.Invoke.
Check out this article WPF Threads Build More Responsive Apps With The Dispatcher
Solution 2
You can use Dispatcher for this. Your code becomes...
private void imgPayment_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
Dispatcher.BeginInvoke(DispatcherPriority.Input, new ThreadStart(() =>
{
try
{
label1.Content = "df";
}
catch
{
lostfocs ld = new lostfocs(up);
// ld.Invoke("df");
object obj=new object();
ld.Invoke("sdaf");
}
}
));
Solution 3
Example
void modi()
{
if(!Dispatcher.CheckAccess())
{
Dispatcher.Invoke(
()=>label1.Content = "df",DispatcherPriority.Normal);
}
else
{
label1.Content = "df";
}
}
Solution 4
I started one non-UI Thread and within this thread I stared one UI thread too. So my requirement is like running an UI thread within a non-UI thread. When handling this scenario I got the following exception. "Exception: The calling thread cannot access this object because a different thread owns it."
In this case I used the Dispatcher.Invoke method of the UI element as follows and it worked well.
if (m_contextWindow == null)
{
System.Threading.Thread newWindowThread = new System.Threading.Thread(new ThreadStart( () =>
{
// Create and show the Window
m_contextWindow = new ContextWindow();
m_contextWindow.DataContext = this;
m_contextWindow.Show();
// Start the Dispatcher Processing
System.Windows.Threading.Dispatcher.Run();
}));
// Set the apartment state
newWindowThread.SetApartmentState(ApartmentState.STA);
// Make the thread a background thread
newWindowThread.IsBackground = true;
// Start the thread
newWindowThread.Start();
}
else
{
this.m_contextWindow.Dispatcher.Invoke(new ThreadStart(() =>
{
m_contextWindow.DataContext = this;
if (m_contextWindow.Visibility == System.Windows.Visibility.Collapsed
|| m_contextWindow.Visibility == System.Windows.Visibility.Hidden)
m_contextWindow.Visibility = System.Windows.Visibility.Visible;
}));
}
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Comments
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Yasser almost 2 years
Whenever I refresh a label, I got this error: The calling thread cannot access this object because a different thread owns it. I tried to invoke but it's failed. I'm using WPF Form.
delegate void lostfocs(string st); private void imgPayment_MouseLeftButtonDown(object sender, MouseButtonEventArgs e) { Thread t = new Thread(modi); t.Start(); } void modi() { try { label1.Content = "df"; } catch { lostfocs ld = new lostfocs(up); // ld.Invoke("df"); object obj=new object(); ld.Invoke("sdaf"); } } void up(string st) { label1.Content = st; }
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Tilak almost 12 yearswhy are u using try catch block ?
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brewmanz over 9 years@Sinatr : Are you saying that it's ok to use BeginInvoke without EndInvoke? Or is it another part of my answer that's wrong? I've checked it and see no errors. Please explain why you made your comment "Obviously wrong answer"
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Sinatr over 9 yearsYou've got comment in another your answer. In wpf
Dispatcher
doesn't have EndInvoke method. -
Endareth about 9 yearsThanks for including the Dispatcher.CheckAccess bit, this was the final step I was missing in a related issue!
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Ievgen about 8 yearsIf someone searching for a problem with setting window owner from other thread: stackoverflow.com/questions/14896111/…