'Cannot GET /' on http://localhost:3000/

[ElAnonimo]

Please help me out fixing this. After gulp serve-build completes Firefox launches with this error message. It seems Firefox doesn't get connected. There is no 'browser connected' output in the console.

[ElAnonimo]

Seems the issue is with the different ports in karma.conf.js:
proxies: { '/': 'http://localhost:8888/' },
// web server port port: 8888,
Though I haven't yet resolved this.