[angular] 'router-outlet' is not a known element

I have a mvc 5 project with a angular frontend . I wanted to add routing as described in this tutorial https://angular.io/guide/router. So in my _Layout.cshtml I added a

<base href="/">

and created my routing in my app.module. But when I run this I get the following error:

Error: Template parse errors:
    '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. ("
    <a routerLink="/dashboard">dashboard</a>
    </nav>
    [ERROR ->]<router-outlet></router-outlet>
     "): ng:///AppModule/AppComponent.html@5:0

In my app.component the line

<router-outlet></router-outlet>

gives an error telling me that Visual studio cannot resolve the tag 'router-outlet'. Any suggestions how I can fix this error? Am I missing a reference or a import or just overlooking something?

Below are my package.json ,app.component and app.module

package.json:

{
    "version": "1.0.0",
    "name": "app",
    "private": true,
    "scripts": {},
    "dependencies": {
    "@angular/common": "^4.2.2",
    "@angular/compiler": "^4.2.2",
    "@angular/core": "^4.2.2",
    "@angular/forms": "^4.2.2",
    "@angular/http": "^4.2.2",
    "@angular/platform-browser": "^4.2.2",
    "@angular/platform-browser-dynamic": "^4.2.2",
    "@angular/router": "^4.2.2",
    "@types/core-js": "^0.9.41",
    "angular-in-memory-web-api": "^0.3.2",
    "bootstrap": "^3.3.7",
    "core-js": "^2.4.1",
    "graceful-fs": "^4.0.0",
    "ie-shim": "^0.1.0",
    "minimatch": "^3.0.4",
    "reflect-metadata": "^0.1.10",
    "rxjs": "^5.0.1",
    "systemjs": "^0.20.12",
    "zone.js": "^0.8.12"
    },
    "devDependencies": {
    "gulp": "^3.9.1",
    "gulp-clean": "^0.3.2",
    "gulp-concat": "^2.6.1",
    "gulp-tsc": "^1.3.2",
    "gulp-typescript": "^3.1.7",
    "path": "^0.12.7",
    "typescript": "^2.3.3"
    }
}

app.module.ts:

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { RouterModule, Routes } from '@angular/router';

import { AppComponent } from './app.component';
import {DashboardComponent} from "./dashboard/dashboard.component"    

const appRoutes: Routes = [
{
    path: '',
    redirectTo: '/dashboard',
    pathMatch: 'full',
    component: DashboardComponent
},  
{
    path: 'dashboard',
    component: DashboardComponent
}
];
@NgModule({
imports: [
    RouterModule.forRoot(appRoutes),
    BrowserModule,
    FormsModule               
],
exports: [RouterModule],
declarations: [
    AppComponent,  
    DashboardComponent      
],
bootstrap: [AppComponent]
})
export class AppModule {

}

app.component.ts:

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

@Component({
selector: 'my-app',
template: `
          <h1>{{title}}</h1>
          <nav>
          <a routerLink="/dashboard">dashboard</a>
          </nav>
          <router-outlet></router-outlet>
          `
})
export class AppComponent {
    title = 'app Loaded';

}

In my case it happen because RouterModule was missed in the import.

It works for me, when i add following code in app.module.ts

@NgModule({
...,
   imports: [
     AppRoutingModule
    ],
...
})

In your app.module.ts file

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

const appRoutes: Routes = [
{
    path: '',
    redirectTo: '/dashboard',
    pathMatch: 'full',
    component: DashboardComponent
},  
{
    path: 'dashboard',
    component: DashboardComponent
}
];

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

}

Add this code. Happy Coding.

Its just better to create a routing component that would handle all your routes! From the angular website documentation! That's good practice!

ng generate module app-routing --flat --module=app

The above CLI generates a routing module and adds to your app module, all you need to do from the generated component is to declare your routes, also don't forget to add this:

exports: [
    RouterModule
  ],

to your ng-module decorator as it doesn't come with the generated app-routing module by default!

Assuming you are using Angular 6 with angular-cli and you have created a separate routing module which is responsible for routing activities - configure your routes in Routes array.Make sure that you are declaring RouterModule in exports array. Code would look like this:

@NgModule({
      imports: [
      RouterModule,
      RouterModule.forRoot(appRoutes)
     // other imports here
     ],
     exports: [RouterModule]
})
export class AppRoutingModule { }

Here is the Quick and Simple Solution if anyone is getting the error:

"'router-outlet' is not a known element" in angular project,

Then,

Just go to the "app.module.ts" file & add the following Line:

import { AppRoutingModule } from './app-routing.module';

And also 'AppRoutingModule' in imports.

There are two ways. 1. if you want to implement app.module.ts file then:

import { Routes, RouterModule } from '@angular/router';_x000D_
_x000D_
const appRoutes: Routes = [_x000D_
  { path: '', component: HomeComponent },_x000D_
  { path: 'user', component: UserComponent },_x000D_
  { path: 'server', component: ServerComponent }_x000D_
];_x000D_
_x000D_
@NgModule({_x000D_
  imports: [_x000D_
    RouterModule.forRoot(appRoutes)_x000D_
  ]_x000D_
})_x000D_
export class AppModule { }

2. if you want to implement app-routing.module.ts (Separated Routing Module) file then:

//app-routing.module.ts_x000D_
import { NgModule } from '@angular/core';_x000D_
import { Routes, RouterModule } from '@angular/router';_x000D_
_x000D_
const appRoutes: Routes = [_x000D_
  { path: '', component: HomeComponent },_x000D_
  { path: 'users', component: UsersComponent },_x000D_
  { path: 'servers', component: ServersComponent }_x000D_
];_x000D_
_x000D_
@NgModule({_x000D_
  imports: [_x000D_
    RouterModule.forRoot(appRoutes)_x000D_
  ],_x000D_
  exports: [RouterModule]_x000D_
})_x000D_
export class AppRoutingModule { }_x000D_
_x000D_
//................................................................_x000D_
_x000D_
//app.module.ts_x000D_
import { AppRoutingModule } from './app-routing.module';_x000D_
_x000D_
@NgModule({_x000D_
  imports: [_x000D_
    AppRoutingModule_x000D_
  ]_x000D_
})_x000D_
export class AppModule { }

Try this:

Import RouterModule into your app.module.ts

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

Add RouterModule into your imports []

like this:

 imports: [    RouterModule,  ]

This issue was with me also. Simple trick for it.

 @NgModule({
  imports: [
   .....       
  ],
 declarations: [
  ......
 ],

 providers: [...],
 bootstrap: [...]
 })

use it as in above order.first imports then declarations.It worked for me.

Thank you Hero Editor example, where I found the correct definition:

When I generate app routing module:

ng generate module app-routing --flat --module=app

and update the app-routing.ts file to add:

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

Here are the full example:

import { NgModule }             from '@angular/core';
import { RouterModule, Routes } from '@angular/router';

import { DashboardComponent }   from './dashboard/dashboard.component';
import { HeroesComponent }      from './heroes/heroes.component';
import { HeroDetailComponent }  from './hero-detail/hero-detail.component';

const routes: Routes = [
  { path: '', redirectTo: '/dashboard', pathMatch: 'full' },
  { path: 'dashboard', component: DashboardComponent },
  { path: 'detail/:id', component: HeroDetailComponent },
  { path: 'heroes', component: HeroesComponent }
];

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

and add AppRoutingModule into app.module.ts imports:

@NgModule({
  declarations: [
    AppComponent,
    ...
  ],
  imports: [
    BrowserModule,
    FormsModule,
    AppRoutingModule
  ],
  providers: [...],
  bootstrap: [AppComponent]
})

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();    
  }));