Hello karthikeyan,

Thank you for the provided details. 

I am still unable to determine what exactly is causing the issue, your code seems to be correct. Can you please provide a small isolated sample, reproducing the behavior you are experiencing, in order to be able to debug it on my side? Thanks.

Hi Maya,

Thanks for your reply, Please find my response below

1. Is the DropDownList nested inside the cell?

          Ans : I have bound the dropdownlist to the cell at serverside code (column type to dropdownlist)

        2.  Could you share the logic in the cell updating event that checks whether the item is already selected?

          function uw_Exp_AfterCellUpdateHandler(gridName, cellId) {
            var cell = igtbl_getCellById(cellId);
            var colkey = cell.Column.Key;

            var curRowIndex = cell.getRow().getIndex();
            var rows = igtbl_getGridById(gridName).Rows;
            var curLine = rows.getRow(curRowIndex);

            var curGridName = "<%=uw_Exp.ClientID%>";
            var curCellId = cellId.substring(cellId.lastIndexOf("_") + 1);

            var grd = igtbl_getGridById(curGridName);
            var actRow = igtbl_getActiveRow(curGridName);

            var rowIndex = actRow.Element.id;
            var curRowId = rowIndex.substring(rowIndex.lastIndexOf("_") + 1);

            var grdRws = grd.Rows;
            var rws = grdRws.length;

            actRow.getCell(0).setValue(eval(curRowId) + 1);

            if (colkey == "Item_Name") {
                if (actRow.getCellFromKey('Item_Name').getValue() != null) {
                    for (i = 0; i <= rws - 1; i++) {
                        if ((curRowId != i) && (actRow.getCellFromKey('Item_Name').getValue() == grdRws.getRow(i).getCellFromKey('Item_Name').getValue())) {
                            alert('This Item already exists');
            
                            
                    }

                }
            }
            }
            }

             3. Which version of our control are you currently using?

                  11.1