How To Cancel Thread

Jun 12, 2009

I am not familiar with threads, but the project I am working on has a bunch of them. There's a thread for the main form, then threads for activities like a calculation, converting files, etc, so that the user can kick off a calculation job and then kick of a conversion job that will run at the same time. Typically, calculations can run for hours and hours; conversions and other threads may only run a few minutes.If the calculation runs into a problem, how do I cancel that thread? It looks like the threads are controlled (driven?) by the main form, but I'm at a bit of a loss.....

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Cancel The Thread Using CancelAsync?

Nov 30, 2009

I found like 100 tutorials for this background worker, but none for my needs I want to cancel the thread using CancelAsync() , but all the tutorials do it only in a loop, like this:

Private Sub BW_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BW.DoWork
For i As Integer = 0 To 30000
If BW.CancellationPending Then
e.Cancel = True

[Code]...

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Cancel Validating In A DataGridView When A User Clicks The Cancel Button?

May 18, 2006

I validate a DataGridView with the CellValidating-eventhandler.That works fine. However, I want to avoid validating when the user presses the Cancel button. In the sequence validation occurs before the event CancelButton.Clicked.

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Cancel Save Event - E.cancel

Sep 21, 2011

i want to do this: when user click save button, the form must be check first..

if user did not insert the required data, user are not allow to save form..

the code:

Private Sub AssetMasterBindingNavigatorSaveItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles AssetMasterBindingNavigatorSaveItem.Click

[Code].....

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VS 2010 Error - Cross-Thread Operation Not Valid: Control TbPlaca1 Accessed From A Thread Other Than The Thread It Was Created On

Aug 13, 2010

In one application, I need use 4 simultaneous threads.When the threads finished, I need to update the text of a TextBox.So, I create 4 Textbox, and I wanna the threads change the text to FINISHED.Each thread change one distinct TB.I use this "example"

Dim Terminados As Integer = 0
Private Sub frmEnviarMensagem_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Timer1.Enabled = True
Timer1.Start()

[code]....

The problem is, I have an error in the red lines.The error is: INVALIDOPERATIONEXCEPTION "Cross-Thread operation not valid: Control tbPlaca1 Accessed from a thread other than the thread it was created on."I don't use cross threading. Each TB only was accessed for the correspondent thread, and for the "main program".

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Cross-thread Operation Not Valid: Control 'Panel1' Accessed From A Thread Other Than The Thread It Was Created On." ?

Nov 3, 2011

This is the error message I am getting:

"Cross-thread operation not valid: Control 'Panel1' accessed from a thread other than the thread it was created on." The reason I am getting this error is because I am opening up a new form and then calling these three things:

Panel1.Show()
Label1.Show()
Label2.Show()

why I get this error message because it doesn't occur normally if I open Form2 after closing Form1, it only occurs when I open Form2 after closing Form4.

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Error - Cross-thread Operation Not Valid: Control 'txt1' Accessed From A Thread Other Than The Thread It Was Created On

Jul 21, 2009

I have done a program using vb2005 to display reading from my microcontroller bs2 board but have encountered some problems. My code are as follows.

Dim Stop_Rx As Boolean
Private Sub btnRead_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRead.Click
SerialPort1.Open()

[code]....

I've encounter an error which is, (Cross-thread operation not valid: Control 'txt1' accessed from a thread other than the thread it was created on.)

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Error : Cross-thread Operation Not Valid: Control 'l_users' Accessed From A Thread Other Than The Thread It Was Created On

Jun 21, 2012

When my client try to connect to server I'm getting this error : Cross-thread operation not valid: Control 'l_users' accessed from a thread other than the thread it was created on.

Private Sub _socketManager_onConnectionAccept(ByVal SocketID As String) Handles _socketManager.onConnectionAccept
l_Users.Items.Add(SocketID)
End Sub

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Threading Progress Bar In .net - Thread Operation Not Valid Control 'ProgressBar1' Accessed From A Thread Other Than The Thread It Was Created On

Feb 17, 2012

Would anyone be able to help me here please. I'm fairly new to VB.net and threading so im just trying to figure out what is happening.When I debug this I am getting the error thread operation not valid: Control 'ProgressBar1' accessed from a thread other than the thread it was created on.

I'm a little lost as to why the error is occuring or how to fix it. I've had to put the progress bar in a separate thread otherwise the GUI crashes

[Code]...

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Waiting For Threads - Thread.join Suspend Execution Of Code On Calling Thread Until Spawned Thread Finishes Or Is Aborted

Sep 2, 2010

My understanding is that thread.join will suspend the execution of code on the calling thread until the spawned thread finishes or is aborted...

With that in mind, I tried this:

For i = 1 to 50
threads = New Thread(AddressOf test)
threads.IsBackground = True
threads.SetApartmentState(ApartmentState.STA)

[CODE]...

However, the rest of the code runs when the loop finishes, not waiting for all the spawned threads to finish. Since the rest of the code needs the threads to finish (otherwise the rest will error).

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Cross-thread Operation Not Valid: Control 'Autocad' Accessed From A Thread Other Than The Thread It Was Created On

Jun 6, 2010

I have written an application that loads a form - frmCad as well as AutoCad. It does this via a class which detects when AutoCad quits.

Friend Class CadApp Private WithEvents AppObject As AcadApplication... Private Sub AppObject_BeginQuit(ByRef Cancel As Boolean) Handles AppObject.BeginQuit RaiseEvent Quit() End SubEnd Class

My main class loads frmCad as well as CadApp.

Public Class Cad Private WithEvents frmCad As CadForm Private WithEvents app As CadApp... Public Sub ShowForm() If frmCad Is Nothing Then frmCad = New CadForm frmCad.Visible = True End Sub... Private Sub app_Quit() Handles app.Quit frmCad.Dispose() frmCad = Nothing .... End Sub

When I debug the program, it stops at frmCad.Dispose()The program continues to execute, but all the code after it fails to work.Looking more carefully I get an error message which contains:-Cross-thread operation not valid: Control 'Autocad' accessed from a thread other than the thread it was created on.

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Cross-thread Operation Not Valid: Control 'label2' Accessed From A Thread Other Than The Thread It Was Created On?

Feb 9, 2011

My error:Cross-thread operation not valid: Control 'label2' accessed from a thread other than the thread it was created on. I want to be able to give my Public RunBot() sub access to edit Labels, buttons, etc without an error.

[Code]...

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Cross-thread Operation Not Valid: Control 'lblStatus' Accessed From A Thread Other Than The Thread It Was Created On

Apr 1, 2010

I'm getting the 'System.InvalidOperationException' error on acccessing a thread from other than where it was created. My code is:

'Required by the Windows Form Designer
Public components As System.ComponentModel.IContainer ' changed from private

[code]....

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Cross-thread Operation Not Valid: Control 'statusHO' Accessed From A Thread Other Than The Thread It Was Created On

Jun 6, 2009

My problem is Cross-thread operation not valid: Control 'statusHO' accessed from a thread other than the thread it was created on.

System.InvalidOperationException was unhandled
Message="Cross-thread operation not valid: Control 'statusHO' accessed from a thread other than the thread it was created on."
Source="System.Windows.Forms"
StackTrace:

[Code]...

i used it and it works fine then. but as it is mentioned its not a good practice to use it. So what should i do? is it ok if i use this as i am not able to use correct practice. Mine application is not for enterprise purpose. its just my class project, and it works fine even if i put application working in background. System works ok. I dont know how to correct this error.As i dont have that much knowlege of threads.

So please guide me how to fix this in correct way otherwise i am force to go for bad programming practice
Please refer to Windows Mobile Developer Center > Smart Device Development Forums > Windows Mobile Development > Appendtext not working for all my code details

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Cross-thread Operation Not Valid: Control 'lv1' Accessed From A Thread Other Than The Thread It Was Created On?

Aug 4, 2009

Cross-thread operation not valid: Control 'lv1' accessed from a thread other than the thread it was created on.

Dim lvi As ListViewItem
For Each lvi In lv1.Items

[code]....

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VS 2010 E.cancel "cancel Is Not A Member Of "System.EventArgs" Error

Mar 13, 2011

Im coding an interest rate calculator and I need a close clause for the textbox and the combo box using e.cancel and im getting a "cancel is not a member of "System.EventArgs" error

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Error Saying "Cross-thread Operation Not Valid: Control 'lblOnline' Accessed From A Thread Other Than The Thread It Was Created On."?

Feb 7, 2011

Ok i have a Form with the following

Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
txtNotepad.Text = LoadFile("notes.txt")

[code].....

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"Cross-thread Operation Not Valid: Control 'TextBox1' Accessed From A Thread?

Sep 18, 2009

When i run the program i am getting the following error in this line TextBox1.Text &= "File Created: " & FullPath & vbCrLf"Cross-thread operation not valid: Control 'TextBox1' accessed from a thread other than the thread it was created on."

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Write In Worker Thread In A Data Table And Rich Text Box in Main Thread

Mar 4, 2009

I'm creating a Client Server application which involves theServer running some scripts in clients and getting back results in an automated way. In Server, other than Main thread, i have 2 worker threads, a) one monitoring response from clients and b) the other scheduling next available job to respective client which executes that job. The issue here is ,I want these worker threads to write the status of their work in the UI(which comes under Main Thread). Also i need to write things in worker thread in a Data table and Rich Text Box in Main thread. But, I can't do so, since it has been blocked to access one thread's function or property directly from others. Is there any work around to do this?

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Creating A Progress Bar That Runs On Another Thread While Keeping Calculation In Main Thread

Nov 12, 2009

Preface: I know this is an unusual/improper way to do this. I can do this with a "real" ShowDialog(), background worker/thread, and so on. I am trying to do specifically what I describe here, even if it is ugly. If this is impossible for X reason, I have created a fancy progress dialog for some of our long running operations. I need to have this dialog shown on a new thread while having processing continue on the calling (UI in most cases) thread.

[Code]...

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Cross-thread Operation Not Valid Control 'FormSplash' Accessed From A Thread Other?

Sep 5, 2009

I need your help on the following. In debugging mode only the program is stopping to the following line "My.Forms.FormMain.HelpProviderMain.HelpNamespace = "Reports.chm"" with the following error ""An error occurred creating the form. See Exception.InnerException for details. The error is: Cross-thread operation not valid: Control 'FormSplash' accessed from a thread other than the thread it was created on.""

I noticed that when I am putting NONE in SPLASH screen option in the properties of the project, there is no problem.I am no familiar with treating that's why can you give me detail instruction how to overcome this annoying problem?

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Cross-thread Operation Not Valid Exception In Single Thread Application?

Nov 14, 2009

I am getting this exception: Cross-thread operation not valid: Control 'TextBoxOutput' accessed from a thread other than the thread it was created on. in a VB 2008 Windows Forms application that I havent specifically made multi-threaded. I have create a sub called Out() like this:

Private Sub Out(ByVal inString As String)
Me.TextBoxOutput.Text += (Me.TextBoxOutput.Text & inString & vbNewLine)
Me.TextBoxOutput.SelectionStart = Me.TextBoxOutput.Text.Length
Me.TextBoxOutput.ScrollToCaret()
End Sub

and I call it from various events to log messages I am getting from my pbx, which I use a third party open source dll to access. The interesting thing to me is that if I run the deployed application (ie, not in the VS IDE) I do not get any exceptions, it's only from within the IDE.if I add the line: Control.CheckForIllegalCrossThreadCalls = False to the form's constructor, the exceptions stop, but a) this seems like a hacky way to get around the issue and b) the application seems to hang sometimes when I have it set this way.

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Cross-thread Operation Not Valid: Control 'FormSplash' Accessed From A Thread Other

Sep 5, 2009

In debugging mode only the program is stopping to the following line "My.Forms.FormMain.HelpProviderMain.HelpNamespace = "Reports.chm""
with the following error ""An error occurred creating the form. See Exception.InnerException for details. The error is: Cross-thread operation not valid: Control 'FormSplash' accessed from a thread other than the thread it was created on.""I noticed that when I am putting NONE in SPLASH screen option in the properties of the project, there is no problem.

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Cross-thread Operation Not Valid: Control 'hiddenrtb2' Accessed From A Thread

Mar 10, 2010

im getting this error and i cant figure it out.

Public Sub mlogin()
Invoke(chkb, New Object() {"disable"})
Invoke(d, New Object() {achidrtb, "", "="})
Invoke(d, New Object() {hiddenrtb2, "", "="})

[code]....

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Call A Method That Started On A Background Thread On The UI Thread Calling BeginInvoke And Passing In A Delegate?

Aug 27, 2011

I am trying to call a method that started on a background thread on the UI thread calling BeginInvoke and passing in a delegate as follows:

Dispatcher.BeginInvoke(Function() UpdateApplicationDataUI())

to call this method:

Private Sub UpdateApplicationDataUI()
...
End Sub

However, I get an error in the call to BeginInvoke (the UpdateApplicationDataUI portion of the delegate is stating "Expression does not produce a value").

Me.Dispatcher.BeginInvoke(Function() New Action(AddressOf UpdateApplicationDataUI))

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BackgroundWorker Thread Communicate With The Primary UI Thread When Encapsulated In A Class?

Jul 1, 2010

A BackgroundWorker thread can pass data to the primary thread. It does it via the RunWorkerCompleted and ProgressChanged events, which I believe run in the primary thread. I would like to encapsulate the BackgroundWorker control in a class so that I can instantiate it more than once. But I don't know how the BGW can then communicate with the primary thread. If the BGW control is within a class, it does not have access to the properties outside the class. In that case, how can the BGW pass data to the thread that instantiated it?

[Code]....

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Current Thread Must Be Set To Single Thread Apartment Sta Mode Before Ole Calls Can B

Apr 21, 2010

I'm getting the following error:"Current thread must be set to single thread apartment sta mode before ole calls can be made"

I am using Speech.Recognition.SpeechRecognizer and using it to open various dialog boxes. It works fine for the first few but on the third one when it calls the InitializeComponent in the Dialog's New, it throws the above error.

Anybody have any clue what causes this or how to fix it? The SpeechRecognizer seems to run on its own thread, so that seems to be at the root of the problem. If I open thedialog with a button click I don't get an error.

[Code]...

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Error - An Attempt Has Been Made To Free An RCW That Is In Use. The RCW Is In Use On The Active Thread Or Another Thread

Jun 6, 2011

I am in a trouble with this error:"An attempt has been made to free an RCW that is in use. The RCW is in use on the active thread or another thread. Attempting to free an in-use RCW can cause corruption or data loss." I am not sure if the RCW-error is related to my problem but I was having this error last January 25. It appears when I am ending my application. I ignored it. The next morning when I resumed coding for my application, the changes I am making does not appear at run-time anymore. Whatever GUI changes I make in my application (at design time), it does not make any effect any longer when I am running the application. What is causing this? I am so afraid if I have to restart my application from the scratch. I have gone far.

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Error: The Calling Thread Cannot Access This Object Because A Different Thread Owns It

Nov 25, 2011

I have am using a Twitter streaming class library, and would like to update a listbox when a new tweet is posted. I have it all set up to the point where a message box will show when a tweet comes in, but when I try to insert this tweet into a listbox I get this error: The calling thread cannot access this object because a different thread owns it. I don't know what I need to do in order to insert this tweet.

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Forms :: Thread Cannot Access Another Thread's Member Directly And UI Updating

Oct 18, 2011

I have a small problem that I am sure is due mostly to my inexperience with threading. I have used simple entirely self-contained threads before, but not to a great extent. I understand the basic laws that surround them, such as how a thread cannot access another thread's member directly, and must use delegates.

[Code]...

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