No parameterless constructor defined for 'Newtonsoft.Json.Converters.StringEnumConverter'

[guanshichao]

2019-08-19 17:48:53.401 26228-26252/com.wismart.mergecity E/Unity: JsonException: No parameterless constructor defined for 'Newtonsoft.Json.Converters.StringEnumConverter'.
at Newtonsoft.Json.Serialization.JsonTypeReflector+<>c__DisplayClass20_0.b__0 (System.Object[] parameters) [0x00000] in <00000000000000000000000000000000>:0
at System.Func`2[T,TResult].Invoke (T arg) [0x00000] in <00000000000000000000000000000000>:0
at Newtonsoft.Json.Serialization.JsonTypeReflector.GetJsonConverter (System.Object attributeProvider) [0x00000] in <00000000000000000000000000000000>:0
at Newtonsoft.Json.Serialization.DefaultContractResolver.InitializeContract (Newtonsoft.Json.Serialization.JsonContract contract) [0x00000] in <00000000000000000000000000000000>:0
at Newtonsoft.Json.Serialization.DefaultContractResolver.CreatePrimitiveContract (System.Type objectType) [0x00000] in <00000000000000000000000000000000>:0
at Newtonsoft.Json.Serialization.DefaultContractResolver.CreateContract (System.Type objectType) [0x00000] in <00000000000000000000000000000000>:0

[guanshichao]

version 9.0.1