Lookup setValue error with CRM Onpremise December 2016 Update

Hi,

After update Onpremise CRM with December 2016 Update, I receive the following error in form load :
Cannot use 'in' operator to search for '39d0ccc5-47a8-e311-9487-000c2902e4c4' in null

The javascript code is executed in form load :
Xrm.Page.getAttribute("customfield").setValue(Xrm.Page.getAttribute("ownerid").getValue());

This code was executed correctly before installing the update

Have you ever encountered this problem
Thank's in advance

Noureddine