error NG6002: Appears in the NgModule.imports of AppModule, but could not be resolved to an NgModule class

Question

Your module is not yet loaded by the Angular Server in node ng serve, so restart your server so the server loads the module that you just added in @NgModule app.module.ts

This error shows when you add component declaration in imports: [] instead of declarations: [], e.g:

declarations: [
  AppComponent,
],
imports: [
  BrowserModule,
  AppRoutingModule,
  SomeComponent <-----------wrong
],

I got this error when I made the bonehead mistake of importing MatSnackBar instead of MatSnackBarModule in app.module.ts.

I made a mistake by adding a service into imports array instead of providers array.

@NgModule({
  imports: [
    MyService // wrong here
  ],
  providers: [
    MyService // should add here
  ]
})
export class AppModule { }

Angular says you need to add Injectables into providers array.

Fixed it by opting out of Ivy as per documentation.

https://angular.io/guide/ivy

Change tsconfig.app.json to opt out of Ivy.

"enableIvy": false

Sometimes when you change/update @NgModule in your project, projects get compiled but changes doesn't get reflect. So, restart once to get expected results if you not get it. ng serve

This works for me:

1) Stop the ng server

2) Reinstall your package

npm install your-package-name

3) Run all again

ng serve