flutter dio: The XMLHttpRequest onError callback was called

Question

I met an error when I am using Dio. Below is my code:

var response = await Dio().post("http://test.worldstreet.cn/service/account/verificationCode/send", data: { "phoneRegion": _phoneRegion, "phoneNumber": _phoneNumber, "action": "$_action" });

Below is the error:

[+1036 ms] Error: DioException [connection error]: The connection errored: The XMLHttpRequest onError callback was called. This typically indicates an error on the network layer. This indicates an error which most likely cannot be solved by the library.
           dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 297:3  throw_
           packages/dio/src/dio_mixin.dart 509:7                                        fetch
           dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 60:31           <fn>
           dart-sdk/lib/async/zone.dart 1666:54                                         runBinary
           dart-sdk/lib/async/future_impl.dart 177:22                                   handleError
           dart-sdk/lib/async/future_impl.dart 850:46                                   handleError
           dart-sdk/lib/async/future_impl.dart 871:13                                   _propagateToListeners
           dart-sdk/lib/async/future_impl.dart 651:5                                    [_completeError]
           dart-sdk/lib/async/future_impl.dart 737:7                                    callback
           dart-sdk/lib/async/schedule_microtask.dart 40:11                             _microtaskLoop
           dart-sdk/lib/async/schedule_microtask.dart 49:5                              _startMicrotaskLoop
           dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 181:7           <fn>

I can't find any references online. I am pretty sure the backend api is 100% ok. I have tried flutter clean.

Please help!

Answer 1

This error is likely caused by CORS policy. You can disable it when debugging application in Chrome using disable-web-security command as described here:

How to solve flutter web api cors error only with dart code?