single-error-route

application.controller.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName:'Ember Twiddle'
});

application.route.js

import Ember from 'ember';

export default Ember.Route.extend({
  actions: {
    error(err) {
      this.transitionTo('custom-error');
    }
  }
});

application.template.hbs

<nav>
  {{link-to 'View User' 'user.view'}}
  {{link-to 'Edit User' 'user.edit'}}
</nav>

{{outlet}}

custom-error.template.hbs

An error was caught.

index.template.hbs

This is the application index.

router.js

import Ember from 'ember';
import config from './config/environment';

var Router = Ember.Router.extend({
  location: config.locationType
});

Router.map(function() {
  this.route('custom-error');
  this.route('user', function() {
    this.route('view');
    this.route('edit');
  });
});

export default Router;

twiddle.json

{
  "version": "0.4.16",
  "EmberENV": {
    "FEATURES": {}
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.1.0",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.1.0/ember-data.js",
    "ember-template-compiler": "2.1.0"
  }
}

user.edit.route.js

import Ember from 'ember';

export default Ember.Route.extend({
  model() {
    throw new Error('No editing users!');
  }
});

user.view.template.hbs

Here's the user view.