Error 500 while fetching document after version Upgrade of both graphiql and graphql.net

[meghaaprasad]

I have upgraded graphql.net library to 4.6.1 and also graphiql version to 2.0.0 but since then I have been facing error when try to open the UI
" The input does not contain any JSON tokens. Expected the input to start with a valid JSON token, when isFinalBlock is true. Path: $ | LineNumber: 0 | BytePositionInLine: 0. FROM Inner Exception: The input does not contain any JSON tokens. Expected the input to start with a valid JSON token, when isFinalBlock is true. LineNumber: 0 | BytePositionInLine: 0. Exception 9248876d-d7c5-4222-94db-3a2691ced550 The input does not contain any JSON tokens. Expected the input to start with a valid JSON token, when isFinalBlock is true. Path: $ | LineNumber: 0 | BytePositionInLine: 0. FROM Inner Exception: The input does not contain any JSON tokens. Expected the input to start with a valid JSON token, when isFinalBlock is true. LineNumber: 0 | BytePositionInLine: 0. , StackTrace Exception: at System.Text.Json.ThrowHelper.ReThrowWithPath(ReadStack& state, JsonReaderException ex)\r\n at System.Text.Json.Serialization.JsonConverter`1.ReadCore(Utf8JsonReader& reader, JsonSerializerOptions options, ReadStack& state)\r\n at System.Text.Json.JsonSerializer.ReadCore[TValue](JsonConverter jsonConverter, Utf8JsonReader& reader, JsonSerializerOptions options, ReadStack& state)\r\n at System.Text.Json.JsonSerializer.ReadCore[TValue](Utf8JsonReader& reader, Type returnType, JsonSerializerOptions options)\r\n at System.Text.Json.JsonSerializer.Deserialize[TValue](String json, Type returnType, JsonSerializerOptions options)\r\n at System.Text.Json.JsonSerializer.Deserialize[TValue](String json, JsonSerializerOptions options)\r\n "