$.cookie not a function (Low variables) line 42

New error: probably because I have upgraded to 2.3.5 + also EE2.6.1.
Error occurs when pressing button to manage variables or button to save changes (necessary to update variables after having made change to text file).

var activate = $.cookie('exp_low_grouplink');
I receive error message $.cookie not a function. (line 42 )

As a result of the error the variable does not get updated after text file changes.
1 person has
this problem