BTW, your thread title does not really cover your problem. You get your error while using YaST > Software > Software Management. That means without doubt that you started YaST with success. It is only in this Software Management part you have a problem.
YaST is much, much more then only Software Management. When you have some spare time, look around there to find out what features of YaST might be useful to you in your future system management actions.