Theme out of date – Got Syntax Error jQuery

Hello,

I have a client whose theme is out of date and we can’t update it. Since updating to WP 4.5 we are getting JQMIGRATE Syntax Error within an old jQuery file associated with the theme.

It is causing built in functions to fail on the site.

jquery.js?ver=1.11.0:2 Uncaught Error: Syntax error, unrecognized expression: .logo a[href*=#]

fa.error @ jquery.js?ver=1.11.0:2fa.tokenize @ jquery.js?ver=1.11.0:2fa.select @ jquery.js?ver=1.11.0:2fa @ jquery.js?ver=1.11.0:2n.fn.extend.find @ jquery.js?ver=1.11.0:2a.fn.find @ jquery-migrate.min.js?ver=1.4.0:2n.fn.init @ jquery.js?ver=1.11.0:2a.fn.init @ jquery-migrate.min.js?ver=1.4.0:2n @ jquery.js?ver=1.11.0:2(anonymous function) @ ut-init.js?ver=2.8.5:1i @ jquery.js?ver=1.11.0:2j.fireWith @ jquery.js?ver=1.11.0:2n.extend.ready @ jquery.js?ver=1.11.0:2K @ jquery.js?ver=1.11.0:2

Any ideas of how to sort this problem or should we carry on pursuing the theme developers?