Cross-thread operation not valid: Control 'richTextBox1' accessed from a thread other than the thread it was created on

Question

I have declared one formClosing event procedure on form closing here is my code.I'm designing a notepad using c# and before closing the form or my notepad app it should ask user whether he/she wants to save it or not ..

private void Form13_FormClosing(object sender, FormClosingEventArgs e)
    {

        if (this.Text == "Untitled-FileEditor")
        {
            if (richTextBox1.Text.Length > 0)
            {
                DialogResult dr = MessageBox.Show("Do u want to save changes to untitled", "FileEditor", MessageBoxButtons.YesNoCancel, MessageBoxIcon.Question);
                if (dr == DialogResult.Yes)
                {
                    saveFileDialog1.FileName = "NewText";
                    saveFileDialog1.Filter = "Text Files(*.txt)|*.txt";
                    DialogResult d = saveFileDialog1.ShowDialog();
                    if (d == DialogResult.OK)
                    {
                        string TextFilePath = saveFileDialog1.FileName;
                        richTextBox1.SaveFile(TextFilePath, RichTextBoxStreamType.PlainText);
                        richTextBox1.Text = "";
                    }
                }
                if (dr == DialogResult.No)
                {
                    //richTextBox1.Text = "";
                    this.Close();
                }
            }
            else if (richTextBox1.Text.Length == 0)
            { this.Close(); }
        }
        else if (this.Text != "Untitled-FileEditor")
        {
            if (richTextBox1.Modified)
            {
                DialogResult dr = MessageBox.Show("Do u want to save changes to " + openFileDialog1.FileName, "FileEditor", MessageBoxButtons.YesNoCancel, MessageBoxIcon.Question);
                if (dr == DialogResult.Yes)
                {
                    saveFileDialog1.FileName = "NewText";
                    saveFileDialog1.Filter = "Text Files(*.txt)|*.txt";
                    DialogResult d = saveFileDialog1.ShowDialog();
                    if (d == DialogResult.OK)
                    {
                        string TextFilePath = saveFileDialog1.FileName;
                        richTextBox1.SaveFile(TextFilePath, RichTextBoxStreamType.PlainText);
                        richTextBox1.Text = "";
                    }
                }
                if (dr == DialogResult.No)
                {
                    //richTextBox1.Text = "";
                    this.Close();
                }
            }
            if (!richTextBox1.Modified)
            {
                this.Text = "Untitled-FileEditor";
                //richTextBox1.Text = "";
                this.Close();
            }
        }
    }

Error showing - An unhandled exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll

Additional information: Cross-thread operation not valid: Control 'richTextBox1' accessed from a thread other than the thread it was created on.

Read the stack trace to see where you're calling something on the wrong thread. — SLaks, Dec 25 '15 at 17:33
sorry I'm in little bit hurry to finish my assignment which i need to submit tomorrow . That's why i named it like that only .. Form13 is my form name — chikun, Dec 25 '15 at 17:36
In this code there is nothing that triggers that exception. When/where is form_closing called? Oh, and we are in a hurry too so don't waste our time... — rene, Dec 25 '15 at 17:37
Please take a look: http://stackoverflow.com/questions/142003/cross-thread-operation-not-valid-control-accessed-from-a-thread-other-than-the . This is exactly your case. — Alexey Chuikov, Dec 25 '15 at 17:38
just give me a answer of simple question bro .. I want to perform some opertion before form closing .. On which event of form i should write the code ? — chikun, Dec 25 '15 at 17:49
Dude what's wrong with u ? I'm new to .Net world. I'm trying as much as i can .. I've not used any words to hurt u bro .. Everybody is participating and answering my question.. Kindly say if u have any solution — chikun, Dec 25 '15 at 18:04

cramopy · Accepted Answer · 2015-12-25T17:52:21.653

0

This means that you are trying to access/modify data from an other thread than it is allowd to.

Please try:

richtextBox1.Invoke(new Action(richtextBox1.Text = "sample text")); //just a sample

Instead of richtextBox1.Text = "sample text" you write the code of the line where the error appears.

Maybe you should perform your actions within OnClosed event:

protected override void OnClosed(EventArgs e)
{
    //your code here
    base.OnClosed(e);
}

edited Dec 25 '15 at 17:52

answered Dec 25 '15 at 17:39

cramopy

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just give me a answer of simple question bro .. I want to perform some opertion before form closing .. On which event of form i should write the code ? – chikun Dec 25 '15 at 17:48
how can i override OnClosing event sir ? – chikun Dec 25 '15 at 17:50
tried above method .. still showing that exception.. and the exception raised in designer.cs file .. "base.Dispose(disposing);" -> on this line – chikun Dec 25 '15 at 17:55
yeah Brother thanx .. this overriden method helped me :) thanx a lot .. I have removed all this.close() functions and it helped me .. thanx a ton .. give this man a cookie – chikun Dec 25 '15 at 18:36
@chikun No problem, that what `SO` is here for :D cookie means upvote? :P – cramopy Dec 25 '15 at 18:38

Cross-thread operation not valid: Control 'richTextBox1' accessed from a thread other than the thread it was created on

1 Answers1