The CCA tries to upload the CUE data files through the 10.1.10.1 interface of the UC500.
This means that if you're accessing the UC500 through the WAN interface (defaults to 192.168.75.2) from ie the SR520, it will fail to reach the CUE site. BUT the CCA will not tell you what is going on. It will just say: Backup of CUE configuration and data failed.
While trying to figure out what was going wrong I ran into several posts on various forums that all specified this issue, but none offered a solution (besides manually updating all files).
The solution is quite simple. You have to make certain that there is path to the 10.1.10.1 interface.
So, start a command prompt (Start -> Run -> cmd -> OK) and type
route add 10.1.10.0 mask 255.255.255.0 192.168.75.2
If you want to be able to also reach the phones:
route add 10.1.1.0 mask 255.255.255.0 192.168.75.2
And there is another interface that the UC500 listens on:
route add 192.168.10.0 mask 255.255.255.0 192.168.75.2
Now the upgrade from the CCA will not cause you any problems.
Note: when you restart your Windows client the routes will be reset to their default.
Just my 2 bits to help out.