Cannot declaremodule in an NgModule as it's not a part of the current compilation Angular

Question

Im not sure what is happening here but i am receiving this error 'Cannot declare 'FormsModule' in an NgModule as it's not a part of the current compilation' when importing 'formsModule' and 'reactiveformsmodule'into my app.module component.

I am running angular 9 and have tried clearing the cache, reinstalling npm. Could these be an angular 9 issue ? would downgrading to 8 fix the problem...

I am confused as to what is going on here as it imported fine the day previous.

app.module.ts

    import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { AppComponent } from './app.component';
import { HttpClientModule } from '@angular/common/http';
import { ExpertAdviceLandingPageComponent } from './expert-advice-landing-page/expert-advice-landing-page.component';
import { InstagramComponent } from './instagram/instagram.component';
import { MDBBootstrapModule } from 'angular-bootstrap-md';
import { SharedModule } from './shared/shared.module';
import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
import { BuyingGuideComponent } from './buying-guide/buying-guide.component';
import { IdeasAndInspirationComponent } from './ideas-and-inspiration/ideas-and-inspiration.component';
import { AdviceAndGuidanceComponent } from './advice-and-guidance/advice-and-guidance.component';
import { GuidesComponent } from './guides/guides.component';
import { CommonModule } from '@angular/common';
import { CarouselComponent } from './carousel/carousel.component';
import { CarouselModule } from 'angular-bootstrap-md';
import { AppRoutingModule } from './app-routing.module';
import { SharedService } from './shared/sharedService';
import { NgbModule } from '@ng-bootstrap/ng-bootstrap';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';

@NgModule({
  declarations: [
    AppComponent,
    BuyingGuideComponent,
    IdeasAndInspirationComponent,
    AdviceAndGuidanceComponent,
    GuidesComponent,
    ExpertAdviceLandingPageComponent,
    InstagramComponent,
    CarouselComponent,
    FormsModule,
    ReactiveFormsModule
  ],
  imports: [
    BrowserModule,
    SharedModule,
    HttpClientModule,
    CommonModule,
    CarouselModule,
    MDBBootstrapModule.forRoot(),
    BrowserAnimationsModule,
    AppRoutingModule,
    NgbModule,
    FormsModule,
    ReactiveFormsModule

  ],
  providers: [SharedService],
  bootstrap: [AppComponent]
})
export class AppModule {
}

Answer 1

When importing modules in Angular it should be placed under the imports array not declarations.

declarations: [
    AppComponent,
    // ReactiveFormsModule---remove from declarations and add in import because its is imported
    // FormsModule`enter code here`---remove from declarations and add in import
],
imports: [
    ReactiveFormsModule,
    FormsModule
]