System.InvalidOperationExcepton: Cross-thread operation not valid

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Hello everyone, I have here a standalone application written using C# language.
Error occured when I hit the button "compute"
Please see below error:

Error Description : System.InvalidOperationExcepton: Cross-thread operation not valid: Control 'label1' accessed froma thread other than the thread it was created on.
at system.windows.forms.control.get_Handle()
at System.Windows.Forms.Control.set_WindowText(String value)
at System.Windows.Forms.Control.set_text(String Value)
at BCCSReportGenerator.frmComputeBCCS.GenerateReport() in D:\PROCUREMENT SYSTEMS BACKUP\TOOLS AND INSTALLERS\PROJECTS\BCCS Tool\Source Code\BCCSReportGenerator\frmComputeBCCS.cs line 62

Thank you very much in advance for your help.

Posted 25-May-11 2:45am

serigraphie

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OriginalGriff · Answer 1 · 2011-05-25T02:49:00

Solution 1

You can only use any control from the UI thread: the thread it was created on. If you aren't on the right thread, then you need to invoke the correct one.

How to: Make Thread-Safe Calls to Windows Forms Controls [^]

[edit]Typo: "controlled" for "created" - OriginalGriff[/edit]

Posted 25-May-11 2:49am

OriginalGriff

Updated 25-May-11 2:50am

v2

Comments

serigraphie 25-May-11 9:10am

Hi OriginalGriff,
Thank you for your response and I will study the link you have given me.
Thank you.

Sergey Alexandrovich Kryukov 25-May-11 11:51am

My 5.

Please see my answer (links) a wider view, more detail on the mechanism.
--SA

Tarun.K.S · Answer 2 · 2011-05-25T02:56:00

Solution 2

In the function where you are updating label1, do this:

C#

this.Invoke(new MethodInvoker(UpdateLabel)); //UpdateLabel is a function where the label will be updated

private void UpdateLabel()
{
 //Do something with the label1
}

Posted 25-May-11 2:56am

Tarun.K.S

Comments

serigraphie 25-May-11 9:09am

Hi Tarun,
Thank you very much for your response and simply answering my question, still I dont get it, I am not the one who did the codes for this, I hope this may help you to help me, here is my code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Threading;

using System.Reflection;
namespace BCCSReportGenerator
{
public partial class frmComputeBCCS : Form
{
object[] _rowsFilledArray = new object[] { 2 };
public delegate void SetRowsFilledDelegate(string val);
public SetRowsFilledDelegate SetRowsFilled;
Thread _oFillThread = null;

public frmComputeBCCS()
{
InitializeComponent();
SetRowsFilled = new SetRowsFilledDelegate(OnSetRowsFilled);
}
public void OnSetRowsFilled(string val)
{
label1.Text = val;
//progressBar1.Value = val;

}
private void frmComputeBCCS_Load(object sender, EventArgs e)
{
//GenerateReport();
label1.Text = "";
label2.Visible = false;
}
private void BeginThread()
{
progressBar1.Maximum = 200;
progressBar1.Minimum = 0;
timer1.Enabled = true;
_oFillThread = new Thread(new ThreadStart(GenerateReport));
//btnExecute.Enabled = false;
_oFillThread.Start();

}
void GenerateReport()
{
try
{
string UserName = StaticObject.UserName;

DataAccess AccessData = new DataAccess();
DataSet _ds = AccessData.PopulateReports(UserName);
if (_ds.Tables[0].Rows.Count > 0)
{
DataTable DT = _ds.Tables[0];
label1.Text = "";
int iCount = 0;
foreach (DataRow row in DT.Rows)
{
DataSet _ds1 = new DataSet();
string ReportName = row[0].ToString();
string DateGenerated = DateTime.Now.ToShortDateString();
_rowsFilledArray[0] = "Computing " + ReportName;
//_rowsFilledArray[1] = DT.Rows.Count.ToString();
this.BeginInvoke(SetRowsFilled, _rowsFilledArray);
//_rowsFilledArray2[0] = iCount;
//this.BeginInvoke(SetRowsFilled2, _rowsFilledArray2);
//BG
if (row[2].ToString() == "Business Group")
{
AccessData.GenerateReport(ReportName, DateGenerated, row[2].ToString(), row[1].ToString(), UserName);
}
else if (row[2].ToString() == "Team")
{
//TEAM
AccessData.GenerateReport(ReportName, DateGenerated, row[2].ToString(), row[1].ToString(), UserName);
}
else if (row[2].ToString() == "Division Managed")
{

//Division Managed
AccessData.GenerateReport(ReportName, DateGenerated, row[2].ToString(), row[1].ToString(), UserName);
}
else if (row[2].ToString() == "Family")
{
//Family
AccessData.GenerateReport(ReportName, DateGenerated, row[2].ToString(), row[1].ToString(), UserName);
}
iCount = iCount + 1;
if (iCount == DT.Rows.Count)
{
timer1.Stop();
}
}
MessageBox.Show("You have

Sergey Alexandrovich Kryukov 25-May-11 11:50am

Right, a 5, please see more detail in my answer (links).
--SA

Sergey Alexandrovich Kryukov · Answer 3 · 2011-05-25T05:49:00

You cannot call anything in UI from a non-UI thread. You can use BeginInvoke or Invoke of System.Threading.Dispatcher (both forms and WPF, preferred) or System.Windows.Forms.Control (Forms only, apparently).

See detailed explanation and samples code in my past asnwers:
Control.Invoke() vs. Control.BeginInvoke()[^],
Problem with Treeview Scanner And MD5[^].

More links on thread use:
How to get a keydown event to operate on a different thread in vb.net[^],
Control events not firing after enable disable + multithreading[^].

—SA