Let me start by saying that I’m probably doing this wrong. So if someone reads this and knows a better way to do this, I’m all ears.
I was having the same problem with jigoshop after upgrading WordPress. However, I found a solution. In the jigoshop plugin folder. Open assets -> js -> jigoshop_backend.js
After you open the jigoshop_backend.js file find this bit of code at the top of the page and delete it:
;(function($){if(/1\.(0|1|2)\.(0|1|2)/.test($.fn.jquery)||/^1.1/.test($.fn.jquery)){alert('blockUI requires jQuery v1.2.3 or later! You are using v'+$.fn.jquery);return;}
Save the file and BAZINGA, it works.