core.js:9798 NG0303: Can't bind to 'ngIf' since it isn't a known property of 'div'. code example

Example 1: core.js:7813 Can't bind to 'ngIf' since it isn't a known property of 'div'

import { CommonModule } from '@angular/common';  
import { BrowserModule } from '@angular/platform-browser';

Example 2: core.js:7813 Can't bind to 'ngIf' since it isn't a known property of 'div'

@NgModule({
    imports: [CommonModule],
    declarations: [MyComponent]
  ...
})
class MyComponentModule {}