I'm added phonegap-plugin-push (http://docs.ionic.io/docs/push-from-scratch) to my project, then after I'm build/run it, the error was appeared.
I've try so many ways (https://github.com/driftyco/ionic-service-push-client/issues/22) (SDK Manager unable to fetch content - Connection to https://dl-ssl.google.com refused), but nothing can help me.
Before I'm added this plugin, my project was fine.