VS 2008 Multi-threding - Adding Multi-threading Facilities - Cross-thread Operation Not Valid
Feb 10, 2010
I'm adding multi-threading facilities for the first time. I have a function that is wrapped to be run in a separated thread. This function retrieves data (text) from a combobox and it works for sure without multi-threading.
When I call it as multi-threaded, I get the following error when I try to retrieve the data from the cmobobox: Cross-thread operation not valid: Control 'cmb1stBL' accessed from a thread other than the thread it was created on.
It looks like a restriction of thread-safety... I assume that the child thread cannot read from his parent, to make sure that he doesn't change his parent data. So how can I read the data from the combobox? Should I read the comoboxbox data before calling the child thread?
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Aug 25, 2009
I looked around the site and the questions I found relating to this subject were for C# (the application that I am maintaining is written in VB.NET), so I apologize if I overlooked one. Here is where I am calling my thread:
[Code]...
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Oct 2, 2009
I have a loop the iterate in my ListBox and I got this error. Cross-thread operation not valid: Control 'ListBox1' accessed from a thread other than the thread it was created on.
Here is my codes:
Private Thread As New System.Threading.Thread(AddressOf myFunc)
Sub myFunc()
Dim i As Integer
[Code]...
My Listbox1 is contain hundreds of lines to loop..thats long iteration. and i need the main form keeps responding from other function even loop is under process. This time i need to use this method of multi-threading.
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Apr 5, 2009
Im trying to work with threading on a project im doing but i have run into this cross-thread problem, ive worked with background workers before and never had this issue.ive done some searching and found some good threads this one in perticular[URL]..now i tried to use these examples and i made it work on a differant project but i cant seem to get my head around how to make it work on this project.
[Code]...
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Oct 3, 2009
[Code] If I wanted to add 3 icons, the LV would add them like it normally would, but then, for some reason, it enters the loop again and that's when it throws this error: ex = {"Cross-thread operation not valid: Control 'ListView1' accessed from a thread other than the thread it was created on."}. I don't understand why, because I'm invoking the LV.
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Apr 21, 2009
I am creating an IDE for a game script with similar functionality as the Visual Studio IDE (at least, some of it). The game script consist of code that looks visually a bit like C code. It uses braces to define the start and end of a 'class' and uses nested braces to define the start and end of an 'event' in a class.
What I want finally is to have two Comboboxes above the text editor, one that lists each Class and the other listing each Event. The comboboxes should also show the Class and Event that the caret is currently in, just like in Visual Studio.I have attached an example of such a script (you can open it with Notepad).However, here is a short example where you can also see how I "defined" classes and events:
class1
{
event1
{
[code]....
As you can see, the classes are the 'names' of each block of code, defined by matching braces { }. The events are the names of each nested block of code, also defined by matching braces { } but inside a class. There is only one level of nesting.As you can also see, the layout can follow the standard C-style layout, or a slightly different layout (using the opening brace on the same line as the class/event name), or even a completely chaotic mess. As long as the braces match correctly, the code is valid.So in short, the large blocks are classes, while the nested blocks are events.
What I want to do, is parse an entire script, and store all the Classes (and eventually, also all the Events, but let's forget about them for now). I want to store the Class name, start position (defined as the start index of the name), end position (defined as the index of the closing brace) and the full text (defined as the text between start and end position, so including the name).
vb.net
Public Class clsClass
Private _Name As String
[code]....
The code works basically by finding every first opening brace (the opening brace of each CLASS, not event), and then loops through the class (using a brace counter to keep track of the nested braces) until it found the last closing brace. It then stores the name, start, end and fulltext in a new clsClass and adds it to the list to return.
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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.
[Code]...
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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
[code]....
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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:
[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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Sep 28, 2010
I've been reading around trying to find out why I'd be getting this exception to no avail.
I'm using Visual Basic 2010.
Briefly, I have a "Settings Panel" form which takes a while to create (it contains a lot of labels and textboxes), so I create it in another thread.
After it's loaded, it can be viewed by clicking a button which changes the form's visibility to True. I use the following subroutine to handle invokes for my controls:
Public Sub InvokeControl(Of T As Control)(ByVal Control As T, ByVal Action As Action(Of T))
If Control.InvokeRequired Then
[Code]....
The SettingsTable.Create() method generates a bunch of Labels and TextBoxes based on the contents of the application settings and adds them to the SettingsTable.
When I click on the ViewSettingsPanel checkbox, I get a cross-thread violation error.
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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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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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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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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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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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May 18, 2007
I want to make an application in VB.NET and I want this application to work as follows, There will be an array of items on which I want to perform a specific operation (MyTask), with the help of multiple threads.For example, say, the array is holding 12 items in it, and I want to create 3 threads to do the work,
Thread 1: Reads the first item from the array and goes to perform the specific operation (MyTask).
Thread 2: Reads the second item from the array and goes to perform the operation MyTask
Thread 3: Reads the third itm from the array and goes to perform the Mytask.
Now once Thread 1 completes the operatin MyTask, I want to assign 4th item from the array to the Thread 1 to continue the process.Once Thread 2 completes the operatin MyTask, I want to assign 5th item from the array to the Thread 2 to continue the process and so on... until all the items from the array is processed. Also, the function taking 5 arguments out of which 4 arguments will be same. Only one argument will vary and it will take the keywords one by one as input parameter.
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Apr 3, 2012
ok here is my code :
[Code]...
What's happening is, i see the threads stop after the function dwnld is completed. So i first check for the state (12 means background and unstarted). On case 12 start the thread and in case 16 (stopped) remove that particular thread and add a different thread like i add 10 above. Also there is a check when the i counter reaches last number, restart the whole loop by assigning i=0.
The program downloads some web pages, the url is passed from the listbox2. The geturl will pass the url and remove it from the list. So when the listbox is empty, exit the for loop. But the above code is running for only 11 times and it does not restart. I tried using a lable and goto but it simple hangs. What i want is to maintain 10 threads to keep downloading the web pages and when the list is empty, exit the function.
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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;
[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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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
[Code]...
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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
[code]...
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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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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