'router-outlet' is not a known element

Try this:

Import RouterModule into your app.module.ts

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

Add RouterModule into your imports []

like this:

 imports: [    RouterModule,  ]

Try with:

@NgModule({  imports: [      BrowserModule,      RouterModule.forRoot(appRoutes),      FormsModule                 ],  declarations: [      AppComponent,        DashboardComponent        ],  bootstrap: [AppComponent]})export class AppModule { }

There is no need to configure the exports in AppModule, because AppModule wont be imported by other modules in your application.

If you are doing unit testing and get this error then Import RouterTestingModule into your app.component.spec.ts or inside your featured components' spec.ts:

import { RouterTestingModule } from '@angular/router/testing';

Add RouterTestingModule into your imports: [] like

describe('AppComponent', () => {  beforeEach(async(() => {        TestBed.configureTestingModule({          imports: [            RouterTestingModule          ],      declarations: [            AppComponent          ],        }).compileComponents();      }));