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Hello guys I try to add text to my text box but didn't work and give this error:
System.InvalidOperationException: 'Cross-thread operation not valid: Control 'log_txtbox' accessed from a thread other than the thread it was created on

What I have tried:

private void Events_ClientDisconnected(object sender, ClientDisconnectedEventArgs e)
    log_txtbox.Text += Environment.NewLine + DateTime.Now.ToString() + e.IpPort + " : " + "quit";
Updated 16-Mar-21 22:20pm

1 solution

You can't update the UI from another thread. Depending on whether you're using WinForms or WPF, the solution is different.

log_txtbox.Invoke(() => 
    log_txtbox.Text += .....;

    log_txtbox.Text += ....;
Share this answer
daniel honarpishe 17-Mar-21 4:36am     CRLF
now give me this error: CS1660 my code : log_txtbox.Invoke(() => { log_txtbox.Text += Environment.NewLine+ DateTime.Now.ToString()+ e.IpPort.ToString()+" : "+"join"; });
#realJSOP 17-Mar-21 4:46am     CRLF
Try doing this: log_txtbox.Text = string.Concat(log_txtbox.Text, Environment.NewLine, DateTime.Now.ToString(), e.IpPort.ToString())," : join");
daniel honarpishe 17-Mar-21 5:01am    
," : "," : join"; now give here error
#realJSOP 17-Mar-21 5:11am    
I gotta say, be a programmer. I corrected my reply when I realized I had made that error, but it would have been just as simple for you to do it on your own.
Maciej Los 17-Mar-21 4:47am    

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