Some of the users of this site have complained that they have problems restoring their own iDevice, either the above error or another error saying that Apple's servers are unavailable. The problem is quite widespread because even in the US there are many owners of iDevices who encounter the same errors when they try to restore. It seems that the iTunes activation servers and the servers that check ipsw compatibility have been having problems for several hours.
No one knows if the problem will be completely solved in the near future, it is possible that it has already been solved, I tried to do a restore and I did not encounter any kind of error. If you encounter difficulties when trying to restore, then be patient, things will be resolved soon.
