Update date field custom module using Zoho Inventory Update Record

Update date field custom module using Zoho Inventory Update Record

I'm trying to update a date field in a custom module inside zoho inventory but keep getting this error:

"code": 6, "message": "syntax.error.invalid.json"

This is how my code looks:

campo_sku = Map();
campo_sku.put("cf_sku_master",i_sku);
campo_sku.put("cf_sku_common",i_sku_common);
campo_sku.put("cf_sku_updated","Yes");
campo_sku.put("cf_date_sku_was_updated",zoho.currentdate);
item_update = campo_sku;
info item_update;
ru = zoho.inventory.updateRecord("cm_po_ref",organizationID,i_recID,item_update,"zoho_inventory");

I've tried different formats for the date and when I do that it gives incorrect date format.
When I run this code without the update of that field it works with no issue.