This happens on many occasions when loading content from the web, but for us, it's most common loading images through Facebook's graph shortcut call.
Something as simple as:
package
{
import flash.display.Loader;
import flash.display.LoaderInfo;
import flash.display.Sprite;
import flash.events.Event;
import flash.net.URLRequest;
import flash.system.LoaderContext;
public class RedirectTestFail extends Sprite
{
private const url:String = 'https://graph.facebook.com/4/picture';
private const context:LoaderContext = new LoaderContext(true);
public function RedirectTestFail()
{
var loader:Loader = new Loader();
loader.contentLoaderInfo.addEventListener(Event.COMPLETE, onComplete);
loader.load(new URLRequest(this.url), this.context);
}
protected function onComplete(event:Event):void
{
this.addChild((event.target as LoaderInfo).content);
}
}
}
Gives a dreaded "SecurityError: Error #2122" error.