Angular 9: Value at position X in the NgModule.imports is not a reference

Question

I upgraded an Angular App from v8 to v9. The project imports a custom UI library using Angular 8 and moment.js.

When I build it:

1. It genera

Answer 1

In my case the issue was related to an imported library, that was not Angular v9 compatible (among other things it was not using deep links to Angular Material and moment.js).

I was lucky as the library is an intern one and I could fix these points and republish it. After that it built without any problems or changes in my project.

Answer 2

#2 happened to me after I accidentally used npm link in a project's folder instead of it's dist folder.

Answer 3

you need to change your custom build of modules, so you need to make analog changes to the ones below, in my case i needed to change:

export class ThemeModule {
  static forRoot(): ModuleWithProviders {
    return <ModuleWithProviders>{
      ngModule: ThemeModule,
      providers: [
        ...NbThemeModule.forRoot(
          {
            name: 'default',
          },
          [DEFAULT_THEME, COSMIC_THEME, CORPORATE_THEME, DARK_THEME],
        ).providers,
      ],
    };
  }
}

to:

export class ThemeModule {
  static forRoot(): ModuleWithProviders<ThemeModule> {
    return {
      ngModule: ThemeModule,
      providers: [
        ...NbThemeModule.forRoot(
          {
            name: 'default',
          },
          [DEFAULT_THEME, COSMIC_THEME, CORPORATE_THEME, DARK_THEME],
        ).providers,
      ],
    };
  }
}

Answer 4

In my case, I think there were some incompatibilities between some of the angular libraries that were imported. I think I previously manually bumped @angular/material to 9.2.3 without bumping the other angular libraries.

When I created a new repository using: ng new test-ng9 and then added angular material ng add @angular/material, there were no compilation issues.

So I took the dependencies that the angular cli included in the temp repo and replaced the ones in my existing repository. Then it worked fine.

Before:

    "@angular/animations": "~9.1.6",
    "@angular/cdk": "9.1.1",
    "@angular/common": "~9.1.1",
    "@angular/compiler": "~9.1.1",  
    "@angular/core": "~9.1.1",
    "@angular/forms": "~9.1.1",
    "@angular/material": "9.2.3",
    "@angular/platform-browser": "~9.1.1",
    "@angular/platform-browser-dynamic": "~9.1.1",
    "@angular/router": "~9.1.1",

After:

    "@angular/animations": "~9.1.6",
    "@angular/cdk": "9.1.1",    
    "@angular/common": "~9.1.6",
    "@angular/compiler": "~9.1.6",
    "@angular/core": "~9.1.6",
    "@angular/forms": "~9.1.6",
    "@angular/material": "^9.2.4",
    "@angular/platform-browser": "~9.1.6",
    "@angular/platform-browser-dynamic": "~9.1.6",
    "@angular/router": "~9.1.6",