getting weird error while using angular ui-router

First I define an array:

$scope.workspaces = [{name: "Traffic Permits", state: "traffic-permits", classname: "tab_table ng-isolate-scope"}];

then I call it:

<a class="{{workspace.classname}}" ng-repeat="workspace in workspaces" 
                 ui-sref="{{workspace.state}}" ui-sref-active="active">{{workspace.name}}
            </a>

Seens pretty straightforward. I am just declaring a menu basically. However I am getting a strange error:

TypeError: a.hashPrefix is not a function
    at Object.href (http://localhost:51188/Scripts/angular-ui-router.min.js:7:11776)
    at Object.y.href (http://localhost:51188/Scripts/angular-ui-router.min.js:7:19457)
    at link.t (http://localhost:51188/Scripts/angular-ui-router.min.js:7:24512)
    at link (http://localhost:51188/Scripts/angular-ui-router.min.js:7:24721)
    at nodeLinkFn (http://localhost:51188/Scripts/angular.js:6711:13)
    at compositeLinkFn (http://localhost:51188/Scripts/angular.js:6105:13)
    at publicLinkFn (http://localhost:51188/Scripts/angular.js:6001:30)
    at $get.boundTranscludeFn (http://localhost:51188/Scripts/angular.js:6125:21)
    at controllersBoundTransclude (http://localhost:51188/Scripts/angular.js:6732:18)
    at ngRepeatAction (http://localhost:51188/Scripts/angular.js:20624:15) <a class="{{workspace.classname}} ng-binding ng-scope" ng-repeat="workspace in workspaces" ui-sref="{{workspace.state}}" ui-sref-active="active">

All help is appreciated thanks.

angular.module('myModule').config(function ($stateProvider, $urlRouterProvider) {
    //
    // For any unmatched url, redirect to /state1
    $urlRouterProvider.otherwise("/traffic-permits");
    //
    // Now set up the states
    $stateProvider
    .state('traffic-permits', {
        url: "/traffic-permits",
        templateUrl: "/admin/permittable"
    });
});

Ok, so I am now using the unminified version of the router. The error is being thrown at:

url = "#" + $locationProvider.hashPrefix() + url;

The error is $locationProvider.hashPrefix() is not a function, what could this be???

I put a break point there. hashPrefix is an empty string.