This error occurs on Angular projects and is cause by a new kind of syntax in *ngFor.

<ion-select>
  <ion-select-option *ngFor="let function in Userfunctions" value="{{ function.function.id }}">{{ function.function.description }}</ion-select-option>
</ion-select>

Gave me this error:

How to solve: Can't bind to 'ngForIn' since it isn't a known property of 'div' 

Change "in" to "to" in the *ngFor like this:

<ion-select>
  <ion-select-option *ngFor="let function of Userfunctions" value="{{ function.id }}">{{ function.description }}</ion-select-option>
</ion-select>