Up until now, people who are not registered as official iOS developers have been able to download and activate the iOS 7 betas onto their devices. It worked by downloading the IPSW for your specific device and then, in iTunes, instead of clicking the Restore button, you clicked on Update instead. A small security glitch within iTunes activation meant that people were able to get past this and activate the betas without a problem.
Image : Activation Error iOS 7
It looks as if Apple has decided its time to start cracking down on these unauthorized installations as some people who are using this method are now reporting activation errors and are finding that they are unable to use iOS 7 betas on their devices. The only way to get out of the problem is to downgrade to iOS 6.1.3 or 6.1.4 if you have an iPhone 5.
Because iOS 7 is still in beta, it is not compatible for restores – the only way to restore from an iOS 7 backup is to wait until the firmware is released to the public. There is no way of downgrading back to an earlier version of the iOS firmware as you can only go back to the latest signed version.
You could check the expiry date on the iOS 7 betas you are using as it may be out of date. If this is the case, you can try using a later a beta and seeing if that works. Beta 3 expired on 29th August so you will need to look at beta 4 and above. It could also be that Apple is having further problems with their activation servers. In the last month or so they have been dogged by problems – a security breach resulted in the closure of their developer’s website for a few weeks; they activation servers went off-line for a while and people were reporting downtime on iTunes and iMessage.
iOS 7 should be released to the public late in September. Apple is reportedly hosting a media event on 10th September during which they will announce their new lineup and dates for releases. On the same day it is thought that they will release the GM version of iOS 7 to developers – this is the version that the public will eventually get to see, providing there are no serious issues with it.
If you cannot wait that long there are ways that you can legally activate your UDID for little money.