We have one Umbraco site which was done in 7.0.3.

Recently we attempted to update to 7.3, which seemed to go OK from a front end perspective, but we had issues with the Umbraco back office doing weird things like the login page not displaying properly.
Inspecting the console in Firebug or the like revealed a whole host of jQuery errors.
Given that the upgrade from 7.0.x is fairly big, we put it down to something we missed and rolled back to 7.0.3 with the intention of trying again later.

Today however, I attempted to update my virtually untouched 7.2.8 test installation to 7.3.1 and have run into the exact same issue. Given that I can't find anything or anyone talking about this problem recently I'm not sure how we're the only ones getting this. Here are the errors coming out from the console when we go to "http://host/umbraco/:

Does anyone have any suggestions about what to check?

ReferenceError: jQuery is not defined


(function(t,e){function i(e,i){var n,o,a,r=e.nodeName.toLowerCase();return"area"...


jquery-...3801249 (line 5, col 2)
TypeError: $ is undefined


$.support.fileInput = !(new RegExp(


jquery....3801249 (line 32, col 5)
TypeError: $ is undefined


$.blueimp.fileupload.prototype.options.processQueue.unshift(


jquery....3801249 (line 39, col 5)
TypeError: $ is undefined


var originalAdd = $.blueimp.fileupload.prototype.options.add;


jquery....3801249 (line 32, col 9)
TypeError: e is not a function


!function(e){"use strict";e(function(){e.support.transition=function(){var e=fun...


bootstr...3801249 (line 6, col 27)
TypeError: $ is undefined


$.fn.tabdrop = function ( option ) {


bootstr...3801249 (line 111, col 2)
ReferenceError: jQuery is not defined


})(jQuery);


LegacyU...3801249 (line 418, col 1)
ReferenceError: jQuery is not defined


})(jQuery);


LegacyS...3801249 (line 73, col 1)
TypeError: UmbClientMgr is undefined


UmbClientMgr.setUmbracoPath('/umbraco');


Applica...e547e43 (line 35, col 5)