On an Ember 2.5.0, how can I transition to an error template without changing the URL?

For reasons which are not important, sometimes our backend server will fail.

For both refreshing the page and requesting support, it would be useful for our application NOT to change the URL in the browser's address bar.

I've tried the following WITHOUT success:

const handleError = reason => {
  let windowLocation = window.location.href
  this.replaceRoute('error', new Ember.Error(reason));
  window.history.pushState(page, title, windowLocation);
};

Any suggestions which might work better?