Flutter - Insecure socket connections are disallowed by platform: 10.0.2.2 - flutter

Question

Since today whenever I try to login my application I get the following error thrown by the Dio package: SocketException: Insecure socket connections are disallowed by platform: 10.0.2.2
I use the following settings to connect:
static BaseOptions options = new BaseOptions(
baseUrl: "http://10.0.2.2:3000", // on android emulator
connectTimeout: 5000,
receiveTimeout: 3000)
And consequently something along the lines of (where I have authentication set-up and functioning properly at /user/login):
var apiLogin = api.dio;
try {
Response response = await apiLogin.post("/user/login",
options: Options(contentType: "application/json"),
data: {"email": email, "password": password});
} on DioError catch (e) {
throw Exception([e]);
}
I have a Node server running on port 3000 which is connected to (containerized) mongodb. When trying the authentication, it immediately has the DioError and I haven't been able to find the cause anywhere online.
Does anyone know what this error is related to?
EDIT [ANSWER]
Thanks to #lyrics for pointing me in the right direction:
From API level 27 and higher, usesCleartextTraffic defaults to false, consequently blocking outgoing http requests, requiring HTTPS.
The solution was to add the following to AndroidManifest.xml:
<?xml version="1.0" encoding="utf-8"?>
<manifest ...>
<uses-permission android:name="android.permission.INTERNET" />
<application
...
android:usesCleartextTraffic="true"
...>
...
</application>
</manifest>
as stated in stackoverflow answer
source: https://developer.android.com/guide/topics/manifest/application-element#usesCleartextTraffic

Answer 1

I have a similar issue with Flutter running on ios Simulator and Android emulator:
SocketException: Insecure socket connections are disallowed by platform:
Inside the Flutter project go to :
To enable in Ios:
ios folder -> runner folder -> info.plist
Then add the following lines to enable HTTP requests:
<key>NSAppTransportSecurity</key>
<dict>
<key>NSAllowsArbitraryLoads</key>
<true/>
</dict>
To enable in Android:
Android folder -> app -> src -> main -> AndroidManifest.xml
Add this permission:
<uses-permission android:name="android.permission.INTERNET"/>
then add the following line inside application tag:
android:usesCleartextTraffic="true"

Answer 2

First add-in AndroidManifest file
add this line in the end before closing tag
<uses-permission android:name="android.permission.INTERNET" />
add this line in the beginning
find this tag and add it first in it
<application
android:usesCleartextTraffic="true"

Answer 3

It seems you newly upgraded to Android 10, Well you probably didn't know that HTTPS is the default connection protocol starting with Android 9 and that all connection not using Https will fail.
Read more https://developer.android.com/training/articles/security-config.html
See this answer here
https://stackoverflow.com/a/50834600/6467637

Answer 4

I was making a call to-
Response response = await get('http://worldtimeapi.org/api/timezone/Asia/Kolkata');
Instead of http I simply replaced it to https and it was fixed.
The new request was-
Response response = await get('https://worldtimeapi.org/api/timezone/Asia/Kolkata');
This fixed the issue for me.