@Lee B you said you were on rc6 right? Does it show you an update for RC7? i was having the same issue as you, parsing error on CA update. Along with some other issues. I also know while on RC6 it did not show me a next branch upgrade.
I downgraded back to RC5, verified everything was working again and decided to upgrade again to see if the problem came back or not. Though when i went to upgrade i noticed the upgrade was actually for RC7. After upgrading to RC7 everything is still working.
I don't know if there was a problem with RC6 or if it was just a coincidence but if nothing else is working, and you don't see a RC7 update, you might try downgrading and then updating again if you feel like it. It at least worked for me