This issue typically happens because the FormsModule has not been imported in the module where you're using ngModel.
Import FormsModule: You should import the FormsModule from @angular/forms in the app.module.ts file (or any module where you're using ngModel).
typescript
import { FormsModule } from '@angular/forms';
Add FormsModule to the imports array: In the @NgModule decorator, add FormsModule to the imports array:
typescript
@NgModule({
imports: [FormsModule],
.
})
export class AppModule { }
Check for other modules: If you're using a feature module, make sure that FormsModule is also imported there. If you are trying to use ngModel in multiple modules (like a shared module or a feature module), remember to import FormsModule in each of them.