Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index
<p>When i am click on update button i got this error 
my update click event </p>

<pre><code>protected void btnUpdate_Click(object sender, CommandEventArgs e)
{
    int idx = Convert.ToInt32(e.CommandArgument);
    GridViewRow gr = gvResTasks.Rows[idx];
</code></pre>

<p>when  idx value is upto 19 it works fine ..when it is greater than 19 this error came..
could you please help me on this</p>

<p>Updatebutton.aspx
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<p>updatebutton.aspx.cs</p>

<pre><code>              protected void btnUpdate_Click(object sender, CommandEventArgs e)
{
   // int idx = Convert.ToInt32(e.CommandArgument);
    int idx = Convert.ToInt32(e.CommandArgument);
    GridViewRow gr = gvResTasks.Rows[idx];

    Label hf = (Label)gr.FindControl("hdEmployeeID");

    string sEmpID = hf.Text;
    lblEmployeeID.Text = sEmpID;
    lblEmployeeID2.Text = sEmpID;

    int Rows = gvResTasks.Rows.Count;
    for (int x = 0; x &lt; Rows; x++)
    {
        GridViewRow tr = gvResTasks.Rows[x];
        tr.CssClass = "WhiteBack";
    }

    ClearMessages();

    gr.CssClass = "TealBack";

    string sSubTaskID = gr.Cells[0].Text;
    lblSubTaskID.Text = sSubTaskID;

    lblSubTaskName.Text = @gr.Cells[1].Text;

    LoadSubTaskInfo();

    Single sProgress = 0;
    Boolean bok = Single.TryParse(lblActualProgress.Text, out sProgress);




    DateTime dPF = DateTime.Parse(lblPlannedFinish.Text);

    if (dPF &gt; DateTime.Now)
    {
        btnFinish.Enabled = false;
    }
    else if (dPF &lt;= DateTime.Now)
    {
        if (sProgress &gt;= 100)
        {
            btnFinish.Enabled = false;
        }
        else
        {
            btnFinish.Enabled = true;
        }
        //btnFinish.Enabled = true;
    }

    panelUpdate.CssClass = "float";
    panelUpdate.Visible = false;
    if (gr.Cells[7].Text != "True")
    {
        panelUpdate.Visible = true;
    }


}
</code></pre>
