蘋果已經關閉之前版本的系統驗證，如果你升級到較高的iOS版本，降級只能恢復到iOS 7.1.1了。下面就提供一下iOS 7.1.1官方固件下載地址：

iPhone：

7.1.1 (4 GSM): iPhone3,1_7.1.1_11D201_Restore.ipsw

7.1.1 (4 8GB): iPhone3,2_7.1.1_11D201_Restore.ipsw

7.1.1 (4 CDMA): iPhone3,3_7.1.1_11D201_Restore.ipsw

7.1.1 (4S): iPhone4,1_7.1.1_11D201_Restore.ipsw

7.1.1 (5 GSM): iPhone5,1_7.1.1_11D201_Restore.ipsw

7.1.1 (5 GSM+CDMA): iPhone5,2_7.1.1_11D201_Restore.ipsw

7.1.1 (5c GSM): iPhone5,3_7.1.1_11D201_Restore.ipsw

7.1.1 (5c GSM+CDMA): iPhone5,4_7.1.1_11D201_Restore.ipsw

7.1.1 (5s GSM): iPhone6,1_7.1.1_11D201_Restore.ipsw

7.1.1 (5s GSM+CDMA): iPhone6,2_7.1.1_11D201_Restore.ipsw

iPad：

7.1.1 (iPad 2 Wi-Fi): iPad2,1_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad 2 GSM): iPad2,2_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad 2 CDMA): iPad2,3_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad 2 New): iPad2,4_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad Mini Wi-Fi): iPad2,5_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad Mini GSM): iPad2,6_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad Mini CDMA): iPad2,7_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad 3 Wi-Fi): iPad3,1_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad 3 CDMA): iPad3,2_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad 3 GSM): iPad3,3_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad 4 Wi-Fi): iPad3,4_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad 4 GSM): iPad3,5_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad 4 GSM+CDMA): iPad3,6_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad Air Wi-Fi): iPad4,1_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad Air Cellular): iPad4,2_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad Air China): iPad4,3_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad Mini 2 Wi-Fi): iPad4,4_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad Mini 2 Cellular): iPad4,5_7.1.1_11D201_Restore.ipsw

7.1.1 (iPad Mini 2 China): iPad4,6_7.1.1_11D201_Restore.ipsw

iPod touch 5G：

7.1.1 (5G): iPod5,1_7.1.1_11D201_Restore.ipsw