$ meteor update (which bumped up the version from 1.3.4.1 to 1.3.4.4)
All templates stopped loading and multiple errors (one per template) appear on the console. All errors are of the form: HTML template does not exists! You can disable this error by following this guide
@milanperovic has right. Every single html must be import. But in my app work:
import templateTabs from ‘client/templates/tabs.html’ without a first slash.
Maybe this is something that should be fix in core of meteor.