Hi @hjeong1200
I can see a few problems here. First one is that you are declaring handsontable cell type configuration object inside the column that is defined as dropdown type. It should be either handsontable or dropdown type, they shouldn’t be combined.
The placeholder will work if the configuration is correct, but it will not show in the dropdown list, as the list is generated from the source data, and placeholder will show only on empty cell as the value is added to the cell editor:
