angular2: Error: TypeError: Cannot read property '...' of undefined
That's because abc is undefined at the moment of the template rendering. You can use safe navigation operator (?) to "protect" template until HTTP call is completed:
{{abc?.xyz?.name}}
You can read more about safe navigation operator here.
Update:
Safe navigation operator can't be used in arrays, you will have to take advantage of NgIf directive to overcome this problem:
<div *ngIf="arr && arr.length > 0">
{{arr[0].name}}
</div>
Read more about NgIf directive here.