How to solve Android P DownloadManager stopping with "Cleartext HTTP traffic to 127.0.0.1 not permitted"?

Create a XML res/xml/network_security_config.xml

<?xml version="1.0" encoding="utf-8"?>
<network-security-config>
    <base-config cleartextTrafficPermitted="true" />
</network-security-config>

Reference this file in your tag Application, inside AndroidManifest.xml. Like:

android:networkSecurityConfig="@xml/network_security_config"