Please add a @Pipe/@Directive/@Component annotation. Error

Not a solution to the concrete example above, but there may be many reasons why you get this error message. I got it when I accidentally added a shared module to the module declarations list and not to imports.

In app.module.ts:

import { SharedModule } from './modules/shared/shared.module';

@NgModule({
  declarations: [
     // Should not have been added here...
  ],
  imports: [
     SharedModule
  ],