Forms :: Cross-thread Operation - Setting Up A Simple Application That Has 2 Variables?
Nov 18, 2011
I'm setting up a simple app that has 2 variables, one from a combobox and one from a textbox.Putting all my code directly in the button1_click sub works just fine, however, I wanted to add a marquee progress bar so I tried to implement a backgroundworker.
[code]...
and call it with Me.Invoke(New SetComboBoxTextDelegate(AddressOf SetComboBoxText), ComboBox1.Text)but it still throws the Cross-thread operation invalid error.
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May 7, 2010
Showing and Hiding Forms from a Console Application causes "Cross-thread operation not valid."
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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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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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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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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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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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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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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.
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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
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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:
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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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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
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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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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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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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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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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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May 14, 2011
I am creating a CHAT interface for my game (when networking, server/client style) and I ran into a little problem..The way it works... I have forms for the SERVER (frmServer) and CLIENTS (frmClient) each of them have a LISTBOX (lbChat) in which I input (lbChat.Items.Add(string)) text as the users type it - in essence a chatbox...
So, let's use the CLIENT as an example (as it is simpler and the concept the same in both client and server cases)The Client form (frmClient) creates a thread that is used to listen for chat messages (via TCP) - so what I did was pass the listbox itself (lbChat) to the thread thus (I thought) solving my problem of writing into the listbox when chat messages arrive (and are caught by the thread and not frmClient of course)Now while debugging the code I get the following exception when my thread attempts to write in the listbox (lbChat) of frmClient General Exception: System.InvalidOperationException: Cross-thread operation not valid: Control 'lbChat' accessed from a thread other than the thread it was created on.
So now the question is how do I work around this cross-thread exception? How do I pass information (chat text) from my listener threads (and there will be multiple of them in the field, one per client) to the centralized listbox (lbChat) on the form?I need some kind of method to transfer information while also reducing the chances of running into contention issues (do I need to use ReaderWriterLock?), thing is I have no clue how to accomplish this task (I thought simply passing in the listbox would allow me to write to it in each of the threads).
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May 22, 2012
I am trying to load data using a backgroundworker using a code snippet that I found. I think that it would all work fine, except that I am getting an error that I am doing a cross thread operation. The task that I am trying to accomplish is loading data for a large dataset when a command (Run Operation) is called so that I can prepare the user that it may take a long time, and I can display a scrolling marque to show them that the program is not frozen. I am using a separate form to display the warning, an OK button, and a scrolling marque.[code]
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Oct 14, 2011
I am developing a application called filecopy(windows application). Inside the form1.vb i am having progressbar. Having one more class called FileCopy. inside the filecopy class i have DirectoryCopy method. it invoke the percentage calculation method(that is in form1.vb) for how many percentage is completed. Each and every time the value. Finally , the percentage value is assign to progressbar.value. AT that thime i am getting cross thread operation is not valid exectption. This is my code;
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May 24, 2010
I may need to give you more info but I am not sure what! I have been using a print queue dll with good results but all of a sudden when I add label and try during the job added event to change the text value of this label I get a threading error!
"Cross-thread operation not valid: Control 'lblPagesT' accessed from a thread other than the thread it was created on."
Where can I go to learn about threading, why does it think its a seperate thread? is it cause its coming from the dll?
Private Sub pmon_JobAdded(ByVal sender As Object, ByVal e As PrinterQueueWatch.PrintJobEventArgs) Handles pmon.JobAdded
System.Threading.Thread.Sleep(1000)
[Code]....
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Mar 18, 2009
I keep recieving cross-thread operation errors, and have read that this is due to my need to change this application (VB.Net Telnet server) to be multithreaded.
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Jul 21, 2011
In response to a "Cross-thread operation not valid: Control 'RecordAddedTextBox' accessed from a thread other than the one it was created on." error I have added a routine obtained from Microsoft Help and that is giving me a compile error. This is my original
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Nov 26, 2010
i am working in vb.net 2005 i have more than 10 vb forms and each form has number of textboxes, and maskedtextboxes, so i have to validate them all. i am using this way that on keypress event of textbox i use this code
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but this is very lengthy code, i mean that on each form i have almost 15 to 20 textboxes, and if i use the same code on each's textbox keypress event so it will be very very lengthy code. so please assist me that how i solve this problem? and how do i use the shortest code?
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Aug 31, 2009
sData1 = SerialPort1.ReadExisting()
Label1.Text = sData1
i want to display sData1 in a label. What is the simple way of doing it?
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Oct 15, 2010
I have a sub which is run in the threadpool with this command:
ThreadPool.QueueUserWorkItem(AddressOf UpdateStatus)And here's the sub:
Public Sub UpdateStatus(ByVal state As Object)
Dim ini As New INIAccess
If ini.INIRead(GetX_Games, "-1", "Patched", "0") = "1" Then
StatusLabel.Location = New System.Drawing.Point(120, 145)
StatusLabel.ForeColor = Color.Green
[Code]...
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Sep 8, 2010
In main thread I create panel(s) (based on some configuration), and then in the next step based on the file type (like video, ppt, image...) I create appropriate controls (dynamically) to show on the forms.
The creation of the control will be done in separate threads (for each file). After creating the control, it throws an error when I try to add that control to the panel (which was created in the main thread), something like cross thread violation, control was accessed from one thread other that it was created.
Can some one please help me in this regard? In this scenario, everything - creating the panels and controls - will be dynamic. Nothing will be static.I tried some of the articles found here on StackOverflow (like, control.BeginInvoke() .. etc), but wasn't able to solve my problem.
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Apr 26, 2012
I have this little app that I want to use a pictruebox.show() when a button_click and then hide after a sub process finishes but I get the below error and unable to figure out how to fix cross-threading,
I get the below error: "Cross-thread operation not valid: Control 'PictureBoxProgressbar' accessed from a thread other than the thread it was created on."
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim CMDThread As New Threading.Thread(AddressOf CMDAutomate)
PictureBoxProgressbar.Show()
CMDThread.Start()
End Sub
[Code]...
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Jun 13, 2010
Yes, I see what you mean. But I had to do it that because I tried to do it this way:
CODE:
but its says "Cross-thread operation not valid: Control 'RichTextBox1' accessed from a thread other than the thread it was created on."
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Apr 28, 2010
I have some controls in a .net 4.0 form - a listbox and a listview item.I also have another thread in the same class which is checking a host for output.It uses delegates to display all incoming data to a richtextbox - this works fine.If the data has a particular signature it sends it to a parser sub in another module.This module tries to update the listbox and listview items with that data after it has manipulated it.The problem is; no data is displayed and no errors are thrown.If I add a msgbox("Test") after the code, it shows the messagebox.If I add a test messagebox inside the delegate function, it shows the messagebox. If I put the same MainForm.ListBox1.Items.Add("Howdy") in a ButtonTest.Click event it adds it correctly.
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