I'm getting the same problem with my 920. I can't rollback from the Preview (which is working poorly on my phone). I also tried the Lumia Software Recovery Tool and it says it can't connect to verify if updates are available. I've tried both tools on several PC's, and they never work. My phone is very unreliable with the Preview. Messaging almost never works, and calls can be problems too. It also broke the bluetooth for connecting to my car.Yes! Even Recovery Tool Recognizes my Phone but then it Checks the Server for available firmware and Says back No Package Available for This PHone!
Thanks. Ive seen other posts with same issue too. One is above on 920 .. Another on630 n mine 730..Interesting. I'll see what I can dig up.
I can't find anything that may account for your issue besides either a problem with your internet connection, or a problem with the servers. Try again every few hours until it works, and tell me what happens. I'll keep looking if nothing works.