hi ... iam getting error in GRIDVIEW control

your error message describe all things that..
you have created event with the name 'gvEG_RowCancelingEdit' and there is no method in your code.

if you want to RowCancelEdit event of gridview then write code for that other wise remove the event name from gridview control in aspx page.

Eg.-

<asp:gridview id="CustomersGridView"
        datasourceid="CustomersSqlDataSource"
        autogeneratecolumns="true"
        autogenerateeditbutton="true"
        allowpaging="true"
        datakeynames="CustomerID"
        onrowcancelingedit="CustomersGridView_RowCancelingEdit"
        onrowediting="CustomersGridView_RowEditing"
        onrowupdated="CustomersGridView_RowUpdated"
        runat="server">
      </asp:gridview>

C# code -(Add event like this)

protected void TaskGridView_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
 {
   //Reset the edit index.
   TaskGridView.EditIndex = -1;
 }

or remove :-

onrowcancelingedit="CustomersGridView_RowCancelingEdit

from gridview if you not required this event.