I have a similar issue. I upgraded from 6.1.2.7. After the upgrade, I logged into the controller using Firefox ver 22. navigating to Wireless > AP Installation , The controller (GUI) shows that my AP104 (all three of them) are IU, meaning unprovisioned. Which they are not. When I click on the provision button, the screen just goes blank and all I see is a white screen. I took a laptop and logged into one of the APs via the console, and verified that the AP is actually still provisioned.
I then launched IE 9, and logged into the controller. The AP Installation page still shows that my APs are UI, however, when I click on the Provision button, I am able to see the provision page.
I think there are at least two issues with this build. 1. browser issues, and 2. incorrect reporting on AP provisioning.
I have reboot all the APs multiples times, I have reboot the controller multiple times and it still did not work.
then when I used IE9 and navigated to the provision page, I noticed that it is requiring to fill in the value of the antenna gain. These fields are empty. So I put in values for the antenna gain, and reboot the APs. It now works and all APs come back up.
So if you come across similar issues when you do your upgrades, you may look to see if there are missing fields in the associated page your dealing with.