DioError [unknown] If the server returns an illegal json

[simonkimi]

Package

dio

Version

5.0.3

Output of flutter doctor -v

[✓] Flutter (Channel stable, 3.7.7, on Microsoft Windows [Version 10.0.22621.1413], locale zh-CN)
    • Flutter version 3.7.7 on channel stable at E:\sdk\flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 2ad6cd72c0 (11 days ago), 2023-03-08 09:41:59 -0800
    • Engine revision 1837b5be5f
    • Dart version 2.19.4
    • DevTools version 2.20.1
    • Pub download mirror https://pub.flutter-io.cn
    • Flutter download mirror https://storage.flutter-io.cn

[✓] Windows Version (Installed version of Windows is version 10 or higher)

Dart Version

2.19.4

Steps to Reproduce

import 'package:dio/dio.dart';

void main() async {
  var dio = Dio();
  final rsp = await dio.get('https://httpbin.org/stream/2');
  print(rsp.data);
}

Expected Result

Returns 200, but with an illegal json.
Because the server returned 200 ok, this request should be completed.
Error handling should be my own responsibility.

{"url": "https://httpbin.org/stream/2", "args": {}, "headers": {"Host": "httpbin.org", "X-Amzn-Trace-Id": "Root=1-64170988-2bab114271cd89057b8db564", "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/112.0", "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8", "Accept-Language": "zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2", "Accept-Encoding": "gzip, deflate, br", "Dnt": "1", "Upgrade-Insecure-Requests": "1", "Sec-Fetch-Dest": "document", "Sec-Fetch-Mode": "navigate", "Sec-Fetch-Site": "none", "Sec-Fetch-User": "?1"}, "origin": "46.232.120.163", "id": 0}
{"url": "https://httpbin.org/stream/2", "args": {}, "headers": {"Host": "httpbin.org", "X-Amzn-Trace-Id": "Root=1-64170988-2bab114271cd89057b8db564", "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/112.0", "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8", "Accept-Language": "zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2", "Accept-Encoding": "gzip, deflate, br", "Dnt": "1", "Upgrade-Insecure-Requests": "1", "Sec-Fetch-Dest": "document", "Sec-Fetch-Mode": "navigate", "Sec-Fetch-Site": "none", "Sec-Fetch-User": "?1"}, "origin": "46.232.120.163", "id": 1}

Actual Result

Unhandled exception:
DioError [unknown]: null
Error: FormatException: Unexpected character (at line 2, character 1)
{"url": "https://httpbin.org/stream/2", "args": {}, "headers": {"Host": "ht...
^

#0      DioMixin.fetch.<anonymous closure> (package:dio/src/dio_mixin.dart:538:7)
#1      _RootZone.runBinary (dart:async/zone.dart:1665:54)
#2      _FutureListener.handleError (dart:async/future_impl.dart:162:22)
#3      Future._propagateToListeners.handleError (dart:async/future_impl.dart:779:47)
#4      Future._propagateToListeners (dart:async/future_impl.dart:800:13)
#5      Future._completeError (dart:async/future_impl.dart:575:5)
#6      _SyncCompleter._completeError (dart:async/future_impl.dart:51:12)
#7      _Completer.completeError (dart:async/future_impl.dart:23:5)

[AlexV525]

This is because the default ResponseType is .json. Set .plain if you don't want to imply any transforms.