I've got the error as well when trying to upgrade, I checked right after it still showed as PS3. After a few minutes I refreshed and it had changed to PS4 and under Account Services there was a button at the bottom to display the code for PSN, another minute later I received mail with the same info.

So if you get an error just give it a few minutes, it's taking a while to process but it's working.

After that you get to download 12GB for the client! @_@