multi dropdown in a grid

The below code is throwing the above error. Please advise a correct way of doing this. using a dropdown column in a Grid. Grid rows are in a foreach loop and dropdown saveinto has another nested foreach loop and how to map the rights values to be able to change the preselected values and save.

rows: a!forEach(
          items: local!sources,
          expression: {
            a!gridRowLayout(
              id: fv!index,
              contents: {
                a!textField(
                  value: local!sources[fv!index].DisplayName,
                  saveInto: local!sources[fv!index].DisplayName,
                  refreshafter: "UNFOCUS"
                ),
                a!textField(
                  value: local!sources[fv!index].FullName,
                  saveInto: local!sources[fv!index].FullName,
                  refreshafter: "UNFOCUS"
                ),
                a!textField(
                  value: local!sources[fv!index].Description,
                  saveInto: local!sources[fv!index].Description,
                  refreshafter: "UNFOCUS"
                ),
                a!multipleDropdownField(
                  label: "",
                  choiceLabels: local!sources[fv!index].Technologies.Name,
                  choiceValues: local!sources[fv!index].Technologies.Id,
                  value: { local!sources[fv!index].Technologies.Id },
                  saveInto:                         a!save(
                          local!sources[fv!index].Technologies,
                          a!forEach(
                            items: save!value,
                            expression: {
                              Id: fv!index,
                              DisplayValue: displayvalue(
                                fv!index,
                                local!sources[fv!item].Technologies.Id,
                                local!sources[fv!item].Technologies.Name,
                                null
                              )
                            }
                          )
                        )
                ),