This documentation page is for Quform version 1 and may not be applicable for Quform 2 click here to visit the documentation for Quform 2.
Download updated version of the jQuery UI Core and Datepicker scripts from here.
Extract the files from the jquery.ui.core.min.zip file, you’ll end up with two files:
Upload these files to the folder wp-content/plugins/iphorm-form-builder/js/jqueryui/ and overwrite the existing files that are there.
Visit the problem web page again, and do a force refresh.