Value at position 5 in the NgModule.imports of AppModule is not a reference (build error Angular2)

Question

I updated Angular from 8 to 9 and and when I am trying to build the project a get this error:

ERROR in src/app/app.module.ts:43:12 - error NG1010: Value at position 5 in the NgModule.imports of AppModule is not a reference: [object Object]

 43   imports: [
               ~
 44     BrowserModule,
    ~~~~~~~~~~~~~~~~~~
...
 62     CoreModule.forRoot(),
    ~~~~~~~~~~~~~~~~~~~~~~~~~
 63   ],
    ~~~
src/app/app.component.ts:14:14 - error NG8001: 'router-outlet' is not a known element:
1. If 'router-outlet' is an Angular component, then verify that it is part of this module.
2. If 'router-outlet' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message.

14   template: '<router-outlet></router-outlet>',
                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

My angular version:

Angular CLI: 9.1.9
Node: 12.16.1
OS: win32 x64

Angular: 9.1.11
... animations, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router
Ivy Workspace: Yes

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.800.6
@angular-devkit/build-angular     0.800.6
@angular-devkit/build-optimizer   0.800.6
@angular-devkit/build-webpack     0.800.6
@angular-devkit/core              8.0.6
@angular-devkit/schematics        9.1.9
@angular/cdk                      8.2.3
@angular/cli                      9.1.9
@angular/material                 8.2.3
@ngtools/webpack                  8.0.6
@schematics/angular               9.1.9
@schematics/update                0.901.9
rxjs                              6.5.5
typescript                        3.8.3
webpack                           4.30.0

My app.module.ts is:

    /**
 * @license
 * Copyright Akveo. All Rights Reserved.
 * Licensed under the MIT License. See License.txt in the project root for license information.
 */
import {MatAutocompleteModule} from '@angular/material/autocomplete';
import {DataService} from './services/data.service';
import { BrowserModule } from '@angular/platform-browser';
import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
import { NgModule } from '@angular/core';
import { HttpClientModule } from '@angular/common/http';
import { CoreModule } from '././@core/core.module';
import { ThemeModule } from './@theme/theme.module';
import { AppComponent } from './app.component';
import { AppRoutingModule } from './app-routing.module';
import { APP_BASE_HREF, LocationStrategy, HashLocationStrategy } from '@angular/common';
import {

  NbChatModule,
  NbDatepickerModule,
  NbDialogModule,
  NbMenuModule,
  NbSidebarModule,
  NbToastrModule,
  NbWindowModule,
} from '@nebular/theme';


import {
  NbPasswordAuthStrategy,
  NbAuthModule,
  NbAuthSimpleInterceptor,
  NbAuthSimpleToken,
  routes,
} from '@nebular/auth';

import { AuthGuard } from './auth-guard.service';
import {
  
  ParkingService,
} from './services/parking.service';
import { RouterModule } from '@angular/router';
import { DashboardComponent } from './pages/dashboard/dashboard.component';

@NgModule({
  
  imports: [
    CoreModule.forRoot(),
    BrowserModule,
    BrowserAnimationsModule,
    HttpClientModule,
    AppRoutingModule,
    
    //RouterModule.forRoot(routes),
    
    RouterModule,
    ThemeModule.forRoot(),

    NbSidebarModule.forRoot(),
    NbMenuModule.forRoot(),
    NbDatepickerModule.forRoot(),
    NbDialogModule.forRoot(),
    NbWindowModule.forRoot(),
    NbToastrModule.forRoot(),
    NbChatModule.forRoot({
      messageGoogleMapKey: 'AIzaSyA_wNuCzia92MAmdLRzmqitRGvCF7wCZPY',
    }),
   
  ],
  declarations: [AppComponent],
  providers: [ParkingService,DataService],
  bootstrap: [AppComponent],
  
})
export class AppModule {
}

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// my app-routing.module.ts

import { ExtraOptions, RouterModule, Routes } from '@angular/router';
import { NgModule } from '@angular/core';
import {
  NbAuthComponent,
  NbLoginComponent,
  NbLogoutComponent,
  NbRegisterComponent,
  NbRequestPasswordComponent,
  NbResetPasswordComponent,
} from '@nebular/auth';

const routes: Routes = [
  {
    path: 'pages',
    loadChildren: () => import('app/pages/pages.module')
      .then(m => m.PagesModule),
  },
  {
    path: 'auth',
    component: NbAuthComponent,
    children: [
      {
        path: '',
        component: NbLoginComponent,
      },
      {
        path: 'login',
        component: NbLoginComponent,
      },
      {
        path: 'register',
        component: NbRegisterComponent,
      },
      {
        path: 'logout',
        component: NbLogoutComponent,
      },
      {
        path: 'request-password',
        component: NbRequestPasswordComponent,
      },
      {
        path: 'reset-password',
        component: NbResetPasswordComponent,
      },
    ],
  },
  { path: '', redirectTo: 'pages', pathMatch: 'full' },
  { path: '**', redirectTo: 'pages' },
  
];

const config: ExtraOptions = {
  useHash: false,
};

@NgModule({
  imports: [RouterModule.forRoot(routes, config)],
  exports: [RouterModule],
})
export class AppRoutingModule {
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// coremodule

import { ModuleWithProviders, NgModule, Optional, SkipSelf } from '@angular/core';
import { CommonModule } from '@angular/common';
import { NbAuthModule, NbDummyAuthStrategy } from '@nebular/auth';
import { NbSecurityModule, NbRoleProvider } from '@nebular/security';
import { of as observableOf } from 'rxjs';

import { throwIfAlreadyLoaded } from './module-import-guard';
import {
  AnalyticsService,
  LayoutService,
  PlayerService,
  SeoService,
  StateService,
} from './utils';
import { UserData } from './data/users';
import { ElectricityData } from './data/electricity';
import { SmartTableData } from './data/smart-table';
import { UserActivityData } from './data/user-activity';
import { OrdersChartData } from './data/orders-chart';
import { ProfitChartData } from './data/profit-chart';
import { TrafficListData } from './data/traffic-list';
import { EarningData } from './data/earning';
import { OrdersProfitChartData } from './data/orders-profit-chart';
import { TrafficBarData } from './data/traffic-bar';
import { ProfitBarAnimationChartData } from './data/profit-bar-animation-chart';
import { TemperatureHumidityData } from './data/temperature-humidity';
import { SolarData } from './data/solar';
import { TrafficChartData } from './data/traffic-chart';
import { StatsBarData } from './data/stats-bar';
import { CountryOrderData } from './data/country-order';
import { StatsProgressBarData } from './data/stats-progress-bar';
import { VisitorsAnalyticsData } from './data/visitors-analytics';
import { SecurityCamerasData } from './data/security-cameras';

import { UserService } from './mock/users.service';
import { ElectricityService } from './mock/electricity.service';
import { SmartTableService } from './mock/smart-table.service';
import { UserActivityService } from './mock/user-activity.service';
import { OrdersChartService } from './mock/orders-chart.service';
import { ProfitChartService } from './mock/profit-chart.service';
import { TrafficListService } from './mock/traffic-list.service';
import { EarningService } from './mock/earning.service';
import { OrdersProfitChartService } from './mock/orders-profit-chart.service';
import { TrafficBarService } from './mock/traffic-bar.service';
import { ProfitBarAnimationChartService } from './mock/profit-bar-animation-chart.service';
import { TemperatureHumidityService } from './mock/temperature-humidity.service';
import { SolarService } from './mock/solar.service';
import { TrafficChartService } from './mock/traffic-chart.service';
import { StatsBarService } from './mock/stats-bar.service';
import { CountryOrderService } from './mock/country-order.service';
import { StatsProgressBarService } from './mock/stats-progress-bar.service';
import { VisitorsAnalyticsService } from './mock/visitors-analytics.service';
import { SecurityCamerasService } from './mock/security-cameras.service';
import { MockDataModule } from './mock/mock-data.module';

const socialLinks = [
  {
    url: 'https://github.com/akveo/nebular',
    target: '_blank',
    icon: 'github',
  },
  {
    url: 'https://www.facebook.com/akveo/',
    target: '_blank',
    icon: 'facebook',
  },
  {
    url: 'https://twitter.com/akveo_inc',
    target: '_blank',
    icon: 'twitter',
  },
];

const DATA_SERVICES = [
  { provide: UserData, useClass: UserService },
  { provide: ElectricityData, useClass: ElectricityService },
  { provide: SmartTableData, useClass: SmartTableService },
  { provide: UserActivityData, useClass: UserActivityService },
  { provide: OrdersChartData, useClass: OrdersChartService },
  { provide: ProfitChartData, useClass: ProfitChartService },
  { provide: TrafficListData, useClass: TrafficListService },
  { provide: EarningData, useClass: EarningService },
  { provide: OrdersProfitChartData, useClass: OrdersProfitChartService },
  { provide: TrafficBarData, useClass: TrafficBarService },
  { provide: ProfitBarAnimationChartData, useClass: ProfitBarAnimationChartService },
  { provide: TemperatureHumidityData, useClass: TemperatureHumidityService },
  { provide: SolarData, useClass: SolarService },
  { provide: TrafficChartData, useClass: TrafficChartService },
  { provide: StatsBarData, useClass: StatsBarService },
  { provide: CountryOrderData, useClass: CountryOrderService },
  { provide: StatsProgressBarData, useClass: StatsProgressBarService },
  { provide: VisitorsAnalyticsData, useClass: VisitorsAnalyticsService },
  { provide: SecurityCamerasData, useClass: SecurityCamerasService },
];

export class NbSimpleRoleProvider extends NbRoleProvider {
  getRole() {
    // here you could provide any role based on any auth flow
    return observableOf('guest');
  }
}

export const NB_CORE_PROVIDERS = [
  ...MockDataModule.forRoot().providers,
  ...DATA_SERVICES,
  ...NbAuthModule.forRoot({

    strategies: [
      NbDummyAuthStrategy.setup({
        name: 'email',
        delay: 3000,
      }),
    ],
    forms: {
      login: {
        socialLinks: socialLinks,
      },
      register: {
        socialLinks: socialLinks,
      },
    },
  }).providers,

  NbSecurityModule.forRoot({
    accessControl: {
      guest: {
        view: '*',
      },
      user: {
        parent: 'guest',
        create: '*',
        edit: '*',
        remove: '*',
      },
    },
  }).providers,

  {
    provide: NbRoleProvider, useClass: NbSimpleRoleProvider,
  },
  AnalyticsService,
  LayoutService,
  PlayerService,
  SeoService,
  StateService,
];

@NgModule({
  imports: [
    CommonModule,
  ],
  exports: [
    NbAuthModule,
  ],
  declarations: [],
})
export class CoreModule {
  constructor(@Optional() @SkipSelf() parentModule: CoreModule) {
    throwIfAlreadyLoaded(parentModule, 'CoreModule');
  }

  static forRoot(): ModuleWithProviders {
    return <ModuleWithProviders>{
      ngModule: CoreModule,
      providers: [
        ...NB_CORE_PROVIDERS,
      ],
    };
  }
}

//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////see error here

Answer 1

I don't know the root cause of the porblem but in my case restarting the server helped. note : every instance of your text editor(i use vs Code) should be closed.

Answer 2

The error seems to say that your reference NgModule Could not be determine

In my case, it was solved by adding

import { NgModule } from '@angular/core';

and after adding NgModule to the imports:[NgModule]