Cannot Restore iPhone

You need to update the iPhone to the latest iOS, as iOS 8.3 is not signed by Apple. If you don't want to update you can go to Settings->General->Reset->Erase al content and settings.

lsebek wrote:

I have been trying to restore my iPhone via iTunes for 2 days, without success. everything seems to be on track until I hit the second window asking me to confirm my request to restore. After acknowledging that, I get the following error message

After I select "More Information", in an effort to discover what is happening, it takes me to a page which steps me through the process of resolving the problem. I completed the first 2 but the third step says that I should disable my security software. I have disabled everything, including the Firewall but still have no success. with the restore.

Have you made sure that your version of iTunes is up to date? You also may want to post this issue in the iTunes for Mac forum.

867 wrote:

You need to update the iPhone to the latest iOS, as iOS 8.3 is not signed by Apple.

And exactly how is the OP supposed to do that if they keep getting an error when trying to do just that?