Error when launching an android build

I am encountering a problem. When I launch an android build I have this error message:
Application Error - net::ERR_CLEARTEXT_NOT_PER MITTED (http://localhost:12096/).

This error follows the upgrade of my application from meteor 1.10.1 to 2.5.6.
This mistake appears only on android (ios works correctly) and regardless of the version of android.
on android 7 I have this error:
Err: Connection refused on http://localhost:12096.

AccessRules are configured as follows:

App. accessRule('http://*', { type: 'navigation' });
App. accessRule('https://*', { type: 'navigation' });

Thank you in advance for your help.

try to add:

App.appendToConfig(`<edit-config file="app/src/main/AndroidManifest.xml"
        <application android:usesCleartextTraffic="true"></application>

in your mobile-config.js

Hello @harry73 ,

thank you for your answer.
I will try your solution and post here soon the result.

for information, although a good answer was not the concern here (thx to @harry73)
Our concern came from the cordova-plugin-meteor-webapp, added two years ago, following concerns we had about rendering engines and new security measures that appeared on Android.