@ViewChild

 In Angular 8+, the @ViewChild() syntax is changed slightly:  

Instead of:  @ViewChild('serverContentInput') serverContentInput: ElementRef; 

use  

@ViewChild('serverContentInput', {static: true}) serverContentInput: ElementRef; 

 The same change (add { static: true } as a second argument) needs to be applied to ALL usages of @ViewChild() (and also @ContentChild() ) IF you plan on accessing the selected element inside of ngOnInit().  

If you DON'T access the selected element in ngOnInit (but anywhere else in your component), set static: false instead!

Note : If you're using Angular 9+, you only need to add { static: true } (if needed) but not { static: false }.

PostedBy: Pankaj_Bhakre