The much-anticipated Apple iOS 17 has been unveiled! However, as Apple releases new iOS versions, it will also stop signing some older iOS versions. This means that sooner or later, your current iOS version will no longer be supported and you may have to upgrade your iPhone to a new firmware version. However, every iOS update comes with its downsides and often bring some problems like iPhone battery draining fast, iPhone keeps freezing, iPhone charging problem, etc.
One way to solve the problems associated with iOS updates is to move back to a known stable version, in other words, downgrade iOS version. But what if Apple has stopped signing the version you intend to downgrade to? How to restore and install unsigned IPSW of that version? This article will tell you the answer!
Part 1: What is Unsigned IPSW?
IPSW is the file extension of Apple’s iPhone mobile operating system. An unsigned IPSW means Apple has stopped supporting the iOS version. iOS users will not be able to restore to unsigned firmware using iTunes.
Due to security concerns, Apple will periodically unsign iOS version and encourages users to use the new features offered by new iOS version updates.
However, new versions of iOS software often cause unpleasant experiences to device performance and functionality. To resolve firmware update errors and problems, reverting to a previous stable iOS version is a common solution.
Part 2: Is It Possible to Restore Unsigned IPSW?
Yes, you can restore your iOS device to unsigned IPSW firmware。 But not through the traditional way like iTunes.
Normally, when you want to upgrade or downgrade iOS version using IPSW restore file, you will do it through iTunes.
During the downgrade process, iTunes will make some verifications and checks with Apple servers to ensure you are restoring a signed IPSW file. Anyone trying to install unsigned IPSW firmware through iTunes will only get an error message.
So, to downgrade to a previous iOS firmware that has stopped being signed by Apple, the basic requirements are:
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a third-party restore software
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the unsigned iOS IPSW file
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SHSH blob file
These requirements will continue to expand below. Read on down.
Part 3: How to Restore Unsigned IPSW?
Method 1: Restore Unsigned IPSW Using SHSH2 Blobs
It is possible to restore unsigned IPSWs with the help of SHSH2 Blobs. These blob files are the digital signatures that Apple places on each IPSW firmware file for each iOS device. When Apple stops signing a particular firmware, it removes the sign (signature) from the firmware so users won't be able to downgrade to it.
Online tools like TSS Saver can help with blob saving. You can start saving the digital signature of your current iOS firmware now for possible future use. For how to save and restore SHSH2 blob files, see the steps below.
Step 1: Connect your iPhone to your Mac or Windows computer using a data transfer cable.
Step 2: Open iTunes on your PC and navigate to the iPhone device information page by clicking the mobile icon at the top screen. Keep clicking on Serial Number until ECID appears. Copy the value next to it.
Step 3: Go to TSS Saver website. Enter your ECID, choose your iPhone model and click Submit. The online tool will automatically save the blob of all available iOS firmware for your iPhone device and provide you with an option to download any of them.
Step 4: Referring to the image below, insert your ECID value and click Submit to see all blob files you've previously saved.
With your blob files ready, you are only halfway done with how to downgrade to unsigned iOS. The next section will show you how to use the unsigned IPSW recovery tool, FutureRestore, to restore unsigned iOS versions.
Method 2: Restore Unsigned IPSW by FutureRestore
FutureRestore is a tool developed for iOS users who want to restore, upgrade, or downgrade to any iOS version that is no longer signed by Apple. But FutureRestore can't do the job alone. It needs the help of other files - the destination unsigned iOS IPSW file you're moving to and the blob file of that said destination iOS firmware.
To restore unsigned IPSW file using FutureRestore, follow the steps below:
Requirements:
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A more recent version of the FutureRestore
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The IPSW file of the unsigned iOS you're restoring to
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The blob file (which you've learned how to save and retrieve in the previous section)
Step 1: Connect your iPhone to your PC, making sure your PC has an internet connection.
Step 2: Put all the 3 items listed in the requirements into one folder.
Step 3: Open up Terminal on your Mac computer or Command Prompt (for Windows users).
Step 4: Drag the unarchived FutureRestore file into Terminal and type - t.
Step 5: Next, drag the blob file into the Terminal interface and type --latest-sep --latest-no-baseband (if your iPhone is not sim-enabled) or --latest-sep --latest-baseband (if your iPhone uses sim).
Step 6: Drag the unsigned iOS firmware into the Terminal screen as well. After performing steps #4 through #6, your terminal or Command Prompt interface should look like the one in the image below.
Step 7: Press Enter and let the downgrade process begin and complete.
Step 8: If the log on the Terminal screen indicated that the process is stuck and failed at recovery mode, simply reenter the line of codes and try it again.
Method 3: The Easiest and Fastest way to Downgrade iOS
Although you can use methods above to downgrade iOS, it will still be risky and terribly complicated. If you have a headache to deal with any technical process, in fact you do have a better option - WooTechy iMaster, which is the easiest and fastest way to downgrade iOS.
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Supports most iOS versions and iPhone models, including the newly launched iOS 17 and iOS 16
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Secure downgrade and upgrade process with no risk of data loss
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Free backup and upgrade, during which you can check compatibility
[Video Tutorial] How to Downgrade iOS?
Steps to Downgrade iOS via WooTechy iMaster:
Step 1: Download and install WooTechy iMaster on your computer. Launch it and connect your iOS device with USB cable. Choose Downgrade iOS.
Step 2: Select the firmware version you want to downgrade, click Next to download it.
Step 3: Once the firmware is downloaded and verified, click Start to begin the downgrade process.
Step 4: When your iPhone has been downgraded successfully, click Done.
Conclusion
While Apple will stop signing some older iOS versions, luckily, if you have saved unsigned IPSW through online tools like TSS Saver, you can still use tools like FutureRestore to restore and install unsigned IPSW to downgrade your iPhone to your preferred, bug-free version of iOS.
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