There is an iPad 2 with iOS 4.3.3 I can not upgrade to iOS 9. When updating via iTunes gives an unknown error 27. I tried on different Macs and through the update and through the recovery, it does not work. PS on the device is jailbreak.
For starters I’ll give you a tip: do not update iOS to iPad 2 until the ninth version. It’s a pity that on the device on iOS 6. So you could install the old versions of almost all the necessary applications, for example, Dropbox, Skype, YouTube, etc. But iOS 4 is an excellent stable system.
After updating instead of quickly working device get a braked tablet, on which it is impossible to work. And if you decide to change the iPad, welcome to our flea market , devices with old firmware there in the price.
But if you need to update the firmware, first make sure that:
1. iTunes has been updated to the latest version;
2. Try to connect the device through different USB ports;
3. Try using different cables to connect.
If after this, when you try to update / restore the firmware, you will get a similar error, things are bad. The most common error 27 occurs when the hardware problem on the device. These can be interruptions in the operation of the Wi-Fi module or damage to the motherboard.
Unfortunately, in such a case, you can not do without a visit to the service center.