Insecure HTTP connections are disabled by default on iOS and Android

Summary

Context

Migration guide

Allowing cleartext connection for debug builds

Additional Information

Timeline

References

Summary

If your code tries to open an HTTP connection to a host
on iOS or Android, a StateException is now thrown with
the following message:

Use HTTPS instead.

Important:
  This change over-restricted HTTP access on local networks beyond the
  restrictions imposed by mobile platforms (flutter/flutter#72723).

This change has since been reverted.

Context

Starting with Android API 28 and iOS 9,
these platforms disable insecure HTTP connections by default.

With this change Flutter also disables insecure connections on
mobile platforms. Other platforms (desktop, web, etc)
are not affected.