After upgrading Angular from 4 to 6, how do I get lazy routes to work?

Question

Angular

There are lazy routes in a project written under Angular 4.
After upgrading to 6, a lot of errors are generated:

ERROR in ./src/$$_lazy_route_resource lazy namespace object
Module not found: Error: Can't resolve '/path/to/project/src/app/lazy/about/about.module.ngfactory.js' in '/path/to/project/src/$$_lazy_route_resource'

And there are many of them, for each route.
Connect like this:

export const AppRoutes: Routes = [
(...) 
  {
    path: 'about-us',
    loadChildren: './lazy/about/about.module#AboutModule'
  },
(...) 
]

import {RouterModule} from '@angular/router';
import {ModuleWithProviders} from '@angular/core';

import {AppRoutes} from './app.routes';
/**
 * @type {ModuleWithProviders}
 */
export const AppRoutingModule: ModuleWithProviders = RouterModule.forRoot(AppRoutes);

And then in app.module.ts AppRoutingModule is added to imports.
I compile as:
ng build --prod --aot --output-hashing=all
As you can see from the error, it tries to look for *.ngfactory.js, which does not exist.
This did not help: https://github.com/angular/angular-cli/issues/11835
How can I fix it?
Thank you very much in advance!