Fix iTunes Restore iPad2 Error 9 Problem

One of my relative’s iPad2 got stuck in the iTunes logo interface and unusable for a while. Just tried to get it restored when connected to iTunes via USB. However, it always auto rebooted after progress bar appeared under the Apple logo.

Tried DFU mode and restore still fails with “Unknown Error 9”. This thread googled suggests the unbelievable culprit: the latest iOS 9.2.1 is incompatible to restore iPad2.

Since older iOS version cannot be signed and updated by Apple now, latest iOS 9.3 beta 4 works fine to restore iPad2 successfully.

Unbelievable.