The GridView fired event RowEditing which wasn't handled

You can fix it by adding an empty event

protected void grd_RowDeleting(object sender, GridViewDeleteEventArgs e)
{

}

Just change the "CommandName" property of the "Edit" or "Delete" button from "Edit" to "Editttt" "Delete" to "Deleteee" (or something else which is relevent to you but make sure it is not "Edit" or "Delete"). It will works fine.