Update Sales order

We're unable to update the sales order using the api (v1), facing errors like `Json is not well formatted` and `Internal error`.
Please look into the issue, I'll provide json object if needed.

P.s zoho sample json request for updating the here ( https://www.zoho.com/inventory/api/v1/#Sales_Orders_Retrieve_a_Sales_Order ) also returning error of invalid json.