Cannot read property 'user' of undefined [duplicate]

Answer 1

Issue :

Because you are trying to display data before its available to the view.

Try this :

<div *ngIf='userProfile?.user'>
<h2>{{userProfile.user.firstname}} {{userProfile.user.lastname}}'s Profile <a href="#"><img src="assets/img/pen.png" alt="pen"></a></h2>
</div>

Answer 2

Use safe operator

<div *ngIf='userProfile?.user'>
<h2>{{userProfile.user.firstname}} {{userProfile.user.lastname}}'s Profile <a href="#"><img src="assets/img/pen.png" alt="pen"></a></h2>
</div>