Maybe your device’s battery wasn’t fully charged when the upgrade process began, or the upgrade process ran the battery down or quite simply a faulty battery. Now that we have knocked off battery as a potential culprit, the next step is to try a hard reset to see if the problem was just i OS crash.
Many issues can result in your device’s battery quickly running out absent your knowledge.
Simply click 'Download' and wait for the process to complete.
Once the download is complete, will automatically start repairing the i OS, except this time you wont be bothered with an i Phone error 21 message!
To ensure this you can use a really easy-to-use and convenient software called - i OS System Recovery.
Your memories and data are all precious and you shouldn't risk them.
So here we're showing you 8 different ways by which you can fix i Tunes error 21 or i Phone Error 21, restore with ease, and continue using your device!
Now before we get to the nitty-gritty's of how to fix i Tunes Error 21, I'm sure you must be won-dering what is i Tunes Error 21 (i Phone Error 21) to begin with, and why does it have this strange obsession with your phone!
You are scared, you grab your computer, you search Google for “i Phone won’t turn on after update” and here you are.
You’re excited to finally try out the i OS 11, to sample the new features Apple announced. Yes, you might have been pretty certain that you had ample battery on your device prior to running i OS 11 upgrade, but let’s make sure we troubleshoot battery first. So, pick up your lightning connector – you can try another lightning connector, port and outlet, just to be triple sure – plug into your charging port and into a power source and leave it for some minutes, preferable an hour. Whether it’s just not turning on, or it doesn’t boot, or the screen is just frozen, a hard reset can be the emphatic answer.
You’ve painstakingly done the upgrade and wait for your phone to reboot so you can see for yourselves what Apple CEO described back in June. It might just be some bad data bits that needs to leave the device’s memory, and why not if it might work for you.
The most common reason for i Tunes Error 21 is that your i Tunes is trying to download the restore files (.ipsw) but is unfortunately being blocked from authentication.
This may be due to a hardware error, or maybe there is a communication failure between your device and the servers.
A hard reset is perhaps the easiest, often-used and most straightforward solution to i Phone problems. You can’t get tired now..device is counting on you.