To fix this error either change the JSON to a JSON array (e.g. [1,2,3]) or change the deserialized type so that it is a normal .NET type code example

Example: Cannot deserialize the current JSON array (e.g. [1,2,3]) into type

var objResponse1 = 
    JsonConvert.DeserializeObject<List<RetrieveMultipleResponse>>(JsonStr);