The GridView 'GridView1' fired event Sorting which wasn't handled

If you got this error message when sorting a Gridview:
The GridView 'GridView1' fired event sorting which wasn't handled.

Then do the following add/changes in your code behind.

Aspx.cs Page:
public SortDirection GridViewSortDirection
{
get
{
if (ViewState["sortDirection"] == null)
ViewState["sortDirection"] = SortDirection.Ascending;
return (SortDirection)ViewState["sortDirection"];
}
set { ViewState["sortDirection"] = value; }
}

protected void Gridview1_Sorting(object sender, GridViewSortEventArgs e)

{
string strSortDir = null;switch (GridViewSortDirection)
{
case SortDirection.Ascending:GridViewSortDirection = SortDirection.Descending;
strSortDir = "DESC";
break;
case SortDirection.Descending:GridViewSortDirection = SortDirection.Ascending;
strSortDir = "ASC";
break;
}
SqlDataSource1.SelectCommand = "SELECT ...... FROM tableName order by " + e.SortExpression + " " + strSortDir;
}

More: http://forums.asp.net/t/1286994.aspx