I previously posted on another issue that was seemingly very similar. It appears as though a couple of folks have had this issue, however mine may be a touch different in some regards.
It is obvious for me that jQuery is not loading at all for the wp-login.php page. It doesn't load either when AGCA is deactivated on the network plugins (this is on a MultiSite instance)... so it's evident that it is that something is precluding the loading of jQuery for this page.
My previous post on the other support that was marked [resolved] was this:
I'm having the same kind of error here, however there is NO inclusion of jQuery on the login page. We are using Headway 3.5, however that should not have bearing on this login page since there are no customizations involved on our theme's end in this regard. When I disable AG Custom Admin and reload likewise there is no jQuery being included in this page.
Here is my console output: http://cl.ly/image/2K2A0L3G2Y21
Additionally, the following is in the debug.log: https://gist.github.com/ylluminate/45685926d8532911ce7e
Would appreciate some insight here.