iOS 15 降級:如何安全輕鬆地進行降級

第 1 部分。您是否已為 iOS 15 降級做好準備?

最新的 iOS 更新已經發布,但用戶已經在抱怨它的一些故障。為了克服這些問題,您可能會考慮進行 iOS 15 降級。不過,您應該退後一步,了解它的影響。例如,降級可能會刪除手機上的所有現有數據,包括照片、應用程序、聯繫人等。因此,在撤消 iPhone 上的 iOS 15 更新之前採取必要的預防措施非常重要。

1.1 備份您的設備

這是在將 iOS 15 降級到以前的穩定版本之前應該注意的最重要的事情。當我們降級 iOS 設備時,它可能最終會刪除其中存儲的所有數據。從媒體文件到應用程序數據——您最終可能會在此過程中丟失手機上的所有現有內容。因此,了解如何從 iOS 15 降級到穩定版本的最佳方法是備份您的手機。這樣,在您完成降級後,您可以通過恢復其備份輕鬆取回您的重要數據。
使用 Dr.Fone 備份 iDevice
  • 1將 iPhone 或 iPad 連接到計算機。
  • 2手動選擇數據類型,或全選。
  • 3點擊“備份”按鈕本地備份設備數​​據。
獨特的功能:
  • 備份整個 iOS 設備,包括其聯繫人、通話記錄、消息、照片、視頻等。
  • 將您的數據從一台設備備份和恢復到另一台(或一個 iOS 版本到另一台),沒有任何兼容性問題。
  • 提取現有的 iCloud 或 iTunes 備份並將其恢復到我們選擇的設備。
  • 預覽備份文件中的數據以有選擇地恢復它。恢復備份時將保留現有數據。

使用 iTunes 備份 iDevice

  • 1啟動更新版本的 iTunes,並將 iOS 設備連接到它。
  • 2轉到其“摘要”選項卡並在“備份”選項卡下找到相關選項。
  • 3單擊“立即備份”按鈕以保存設備的備份。
注意事項:
  • iTunes 無法恢復較低版本的較高版本的備份。因此,您必須先備份您的設備,然後再將其升級到 iOS 15。
  • 沒有規定預覽數據並有選擇地恢復它。
  • iTunes 會在恢復備份時擦除 iPhone 上的現有數據。

1.2 了解iOS降級的時間限制

降級iOS版本的整個過程是時間敏感的,很多用戶都沒有意識到這一點。讓我們詳細談談這個。

  • 如果您安裝了 iOS 測試版,那麼您可以隨時將 iOS 測試版降級到以前的穩定版本(直到官方公開的 iOS 版本發布)。
  • 在穩定的公共 iOS 版本發布後,您只有 14 天的時間將您的設備降級到以前的現有 iOS 版本。

1.3 選擇正確的版本從iOS 15降級

理想情況下,您只能將 iOS 15 降級到以前的穩定版本。例如,如果您希望進行 iOS 15 降級,那麼您只能返回到之前由 Apple 簽署的穩定版本。您可以訪問IPSW.me以檢查兼容的固件是否可用。

1.4 知道如何降級到不再由 Apple 簽名的版本(如有必要)

如您所知,要降級 iOS 15,您需要在其正式發布後的 14 天內採取必要的步驟。此外,用戶只能回滾到以前的穩定版本。不過,如果您已經過了 14 天的期限並想降級到不再由 Apple 簽名的版本,那麼您需要使用第三方工具。借助 TinyUmbrella 或 TaigOne Downgrader 等工具,您可以在設備上安裝任何支持的 iOS 版本。它們模仿 Apple 的簽名,讓我們在 iDevices 上安裝個性化固件(iOS 版本)。

儘管整個過程非常技術性,並且可能不會產生積極的結果。由於 Apple 不支持這些第三方工具,因此您需要越獄您的設備才能執行此操作。不建議這樣做,因為它會影響您設備的保修,並且您也將無法再訪問官方 iOS 版本。此外,它會使您的設備容易受到不必要的安全威脅。

第 2 部分。 如何安全降級 iOS 15?

現在,當您了解降級 iOS 15 的所有先決條件時,您可以輕鬆滿足您的要求。理想情況下,您可以藉助 iTunes 或任何其他第三方工具來學習如何從 iOS 15 降級。無論如何,請確保事先對您的設備進行了備份。為了讓您更輕鬆,我們提供了兩種用於進行 iOS 15 降級的解決方案。

2.1 一鍵降級iOS 15解決方案

升級到 iOS 15 的步驟:
  • 將您的 iOS 設備連接到 PC 並啟動 Dr.Fone。
  • 單擊“修復”模塊,然後轉到 iOS 修復選項。
  • 選擇任一模式並通過選擇顯示的 iOS 版本確認您的選擇,然後單擊“開始”。
  • 坐下來等待一段時間,因為應用程序將開始為您的 iOS 設備下載兼容的固件。
  • 注意:請在降級前檢查https://ipsw.me/product/iPhone以確保兼容的固件可用。

drfone android box
Dr.Fone - 系統修復 (iOS)
  • 通過刷新以前的固件更新到 iOS。
  • 還可以在您的 iDevices 上更新 iOS。
  • 不依賴iTunes。
  • 修復所有 iOS 系統問題,如 iOS 凍結、白色 Apple 標誌等。

2.2 使用 iTunes 降級 iOS 15

Though, there are a lot of users who wish to take the assistance of iTunes to do the same. While you can perform iOS 15 downgrade with iTunes, it has its own cons. For instance, you might end up losing the existing data on your phone as it would restore your device to its factory settings. The process is also a bit technical, and you might end up damaging your device in the process.

What you need:
  • The latest version of iTunes
  • IPSW file you wish to install
Steps to downgrade iOS 15 with iTunes
  • Beforehand, Find my iPhone service on your device should be turned off. To do this, unlock it and go to its iCloud Settings > Find my iPhone to disable it. You need to enter your Apple ID and password to confirm this.
  • Now, connect your iOS device to the system and launch an updated version of iTunes on it. Click on the device icon and select your iPhone/iPad.
  • Go to its “Summary” tab and hold the Option Key (on Mac) or the Shift Key (on Windows) while clicking on the “Update” button.
  • This will open a browser window, letting you go to the location where the downloaded IPSW file is saved.
  • Select and load the IPSW file on iTunes and confirm your choice to forcefully update the connected device. Wait for a while and let iTunes complete the iOS 15 downgrade.
operate with itunes

Part 3. Best iOS 15 Downgrading Tools

As you can see, sometimes it can be tough to undo an iOS 15 update on iPhone or iPad. To make the entire process simpler, there are tons of third-party tools that you can try. Not only will they let you downgrade iOS version without losing data, but they would also yield better results. Also, if you have a jailbroken device, then you can even downgrade it to any previous iOS version. Let’s get to know more about the features and flexibility of some of these readily available tools.

3.1 Downgrading Tools for Common People (Fast & Easy to Use)

If you are a beginner and do not have a lot of technical knowledge about iOS downgrading, then consider picking either of the following tools.

3.2 Downgrading Tools for Tech-savvy Users (Complex But Can Achieve More)

If you want more flexibility with your device and have decent technical experience, then you can also explore some of these options too.

tips

What are SHSH blobs for iPhone?

Both SHSH and SHSH2 blobs are referred to digital signatures deployed by Apple on respective IPSW files. This protects the authenticity of the IPSW files and only signed software would be installed on the device. When Apple releases a new iOS version, it stops signing the previous version. In this way, users need to upgrade to the latest public iOS version. This is where previously saved SHSH blobs are used to forge these signatures in order to downgrade our devices.

Part 4. iOS 15 Downgrading Troubleshooting

4.1 iOS 15 Downgrade Failed Many Times

This is one of the most common issues that users face while downgrading their iOS devices. The chances are that while downgrading your device, the process would stop in between unexpectedly.

It happens when we try to downgrade the device to an incompatible iOS version. A faulty internet connection or low free space on the device can also trigger it.

Quick Fixes:
  • Check the iOS version: Needless to say, if you are trying to downgrade your device to an iOS version it no longer supports, then you might face unwanted issues. Ideally, you should try to downgrade iOS 15 to a previous version and not any other existing one.
  • Have a stable internet connection: An inconsistent internet connection is another prominent cause for this error. It happens when the download of the iOS update is halted in between (due to a poor connection). Therefore, make sure that the device stays connected to a working and fast internet connection for a seamless downgrading. You can go to your phone’s WiFi settings to further diagnose this.

4.2 iOS Stuck in Recovery/DFU Mode/Apple Logo

While downgrading your device, your phone might get stuck in the recovery mode, Apple logo, or the DFU mode screen. The situation might seem a bit tedious, but you can try to resolve it by forcefully restarting your phone in most of the cases.

Downgrading from an unstable version, the download process of the firmware update has been halted in between, or any other firmware related issue.

Quick Fixes:
  • Forcefully restart your device: By applying the correct key combinations, we can forcefully restart an iOS device and resolve this issue. Since it resets the current power cycle of the device, it is also known as a soft reset. If you own an iPhone 6s or an older generation phone, then long press the Power and Home button for at least 10 seconds. Users with an iPhone 7 or iPhone 7 Plus can press the Power and the Volume Down button. Keep pressing them until your phone restarts. For iPhone 8 and newer versions, you need to quick-press the Volume Up button first. Let it go and quick-press the Volume Down button. Subsequently, hold the Side button and let it go once the phone restarts.
  • Connect it to iTunes: In case if your phone is stuck in recovery or DFU mode, and you haven’t connected it to iTunes, then do the same. In no time, iTunes will automatically detect that your device is in the recovery mode and display the following prompt. Just confirm your choice and restore your device to factory settings to fix this.

4.3 iOS 15 Downgrade stuck on “Attempting data recovery”

The final step in the downgrading process is when the existing data on the device is recovered. Though, while doing so, the device might get stuck in the process and end up in the same loop.

An incompatible iOS version, loose connections, jailbroken device, lack of free storage, or any other related issue.

Quick Fixes:
  • Check whether your iPhone is jailbroken: Mostly, users get this error while performing iOS 15 downgrade on a jailbroken device. If your device is jailbroken, then you should not use iTunes to downgrade it. Instead, use a readily available tool like iFaith or TinyUmbrella to do the same.
  • Boot your iPhone in Recovery Mode: You can also take the assistance of iTunes and boot your device in the Recovery Mode to resolve this problem. To do this, just launch iTunes on your system and connect your phone to it. Now, using the correct key combinations, forcefully restart your device (already listed above). Subsequently, iTunes will detect as soon as your phone boots in the Recovery Mode. When you get the following prompt, click on the “Restore” button to reset your device.
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4.4 iOS 15 Downgrade with iTunes won’t work

Most of the users take the assistance of iTunes (and an IPSW file) to downgrade iOS 15. Though, if there is a problem with the file, your device, or iTunes, then the process might not work.

An unsupported version of iTunes, corrupt IPSW file, or conflict with the device itself can result in this error.

Quick Fixes:
  • Check the IPSW file: Firstly, make sure that you have downloaded the correct IPSW file from a trusted source. Also, the IPSW file should be compatible with your iOS device else you might face this issue.
  • Disable Find my iPhone: Before you connect your device to iTunes, make sure that the Find my iPhone feature is disabled in it. To do this, go to its iCloud Settings > Find my iPhone and simply turn off this feature. This will not cause any conflict when you undo an iOS 15 update on iPhone.
  • Update iTunes: Needless to say, you should use an updated version of iTunes to downgrade iOS 15. Just launch iTunes on your system and go to Help > Check for Updates. This will make iTunes check for any available update. After finishing the update, you can restart your system and reconnect your device.

4.5 iPhone stuck in a loop trying to restore during downgrade

While restoring the device during the downgrading process, your device might get stuck. For instance, it can get stuck in a restart loop, not letting you access the device.

Lack of free space on the device, corrupt storage, incomplete update, bad IPSW file use, or any other compatibility issue.

Quick Fixes:
  • Force restart your device: This will reset the present power cycle of your device and will let you fix any minor issue related to it. To do this, you need to press certain keys on your device. We have already listed the correct key combinations to force restart a device in the previous sections.
  • Restart the process: If the downgrading process has been halted in between and your phone keeps restarting, then force restart it first. Now, connect it to iTunes or use any other third-party tool to undo an iOS 15 update on iPhone all over again.
  • Use a 3rd party tool: If nothing else seems to work, then consider using a dedicated iOS repairing tool like Dr.Fone - System Repair (iOS). It can fix all kinds of iOS and iTunes related issues without causing any harm to your device. Just launch the application and follow a simple click-through process to put your phone out of the loop and downgrade it to a stable iOS version.

4.6 iOS 15 Downgrade won’t work using SHSH

SHSH Blobs are Apple signatures that are needed to downgrade iOS 15 in a timely manner. Their absence or a wrong SHSH entity can tamper with the downgrading process.

Wrong SHSH blob, corrupt unit by a third-party dump, or an expired SHSH blob can be some of the major reasons for this.

Quick Fixes:
  • Use an SHSH blobs dumper: There are tons of readily available third-party SHSH dumpers (like iFaith) that you can try. Though, most of these applications will require a jailbroken device. You can simply connect your device or provide its model to obtain an ideal SHSH blob.
  • Obtain your device’s SHSH blob: You can connect your iPhone/iPad to the system and launch iTunes on it. Select your device and go to its Summary. Click on the “Serial Number” field a few times, till it displays the ECID number. Now, copy the ECID code and go to any online source to convert it into hexadecimal code.

4.7 Lost all data after iOS 15 Downgrade

This is one of the worst nightmares for any iOS user. After completing the downgrade, the chances are that you might end up losing all the saved photos, videos, contacts, messages, and other important files from your phone.

The process could be halted in between, a corrupt device, bad firmware, and so on. An upgrade to an unstable release of iOS can also cause data loss on your device.

Quick Fixes:
  • Use a data recovery tool ASAP: If you have suffered from an unwanted data loss on your device, then take the assistance of an iOS data recovery program . A part of the Dr.Fone toolkit, it is one of the first and the most successful data recovery tools for iOS devices. All you need to do is connect your device and launch the application. Follow a simple click-through process to extract all kinds of lost or deleted data from your device. The application will let you preview the extracted data, letting you selectively save it to the location of your choice.

4.8 Backup cannot be restored after iOS 15 downgrade

Even after losing their data while downgrading an iOS device, users try to restore an existing backup. Sadly, there are times when the previous iTunes or iCloud backup ceases to restore on the downgraded device.

The problem usually occurs due to a compatibility issue among various iOS versions. For instance, you could have taken the backup of your device when it was running on another iOS version and now you are trying to restore it on an unsupported iOS version.

Quick Fixes:
  • You can load a previous iTunes or iCloud backup using a iOS restoring tool and even preview its data on its interface. For instance, to restore an iCloud backup, you simply need to log-in to your iCloud account. The application will list the available backup files for you pick an ideal option. In this way, you can easily restore your data without erasing the existing content on your device.

Part 5. FAQs about iOS 15 Downgrade

Yes, you can downgrade iOS to a previous version signed by Apple. Users get 14 days after a public official release to do it. If you have upgraded your device to a version, then you can downgrade to a stable version easily (until 14 days after the release of its stable version).

There are all kinds of ways to undo an iOS 15 update on iPhone. If you want, you can take the assistance of iTunes to do the same. Though, to downgrade iOS 15 without losing data, consider using a more sophisticated tool like Dr.Fone - System Repair (iOS). In case if you have a jailbroken device, then you can even give tools like TinyUmbrella a go.

When we install an iOS version on the device, the Apple server asks for a digital signature to authenticate it. A signed IPSW file would have a verified signature issued by Apple, letting us upgrade/downgrade the device without any hassle. Therefore, if an IPSW file is not signed by Apple, then it will not be recognized by the server and the upgrading/downgrading process won’t be completed.

There are all kinds of SHSH dumps and readily available third-party tools that can help us force Apple’s signature and create SHSH blobs even after Apple stops signing them. Though, you should know that Apple might revoke the authentication of such SHSH blobs anytime. To do this, you need to have a jailbroken device and use a dedicated tool like iFaith or FutureRestore.

The Apple Software Program lets us test the releases of iOS before the public availability. You can join or leave the program anytime you want without spending anything. If you want to leave it, then go to the Unenroll section of the website.

apple beta program

Ideally, you can’t downgrade your device to an unsigned iOS version. This is because the Apple server won’t authenticate your downloading request without a valid SHSH blob. That is why users take the assistance of a previously saved SHSH blob to do the same. You can also use a third-party downgrading tool to do it as well.

After downgrading an iOS update, you might find an existing software profile on your device storage. To remove this, just go to your device’s Settings > General > Profile and select the iOS profile from here. Tap on the “Delete Profile” option and confirm your choice to remove it.

You can restore a previously stored SHSH blob from your device or forge Apple’s signature. There are a few third-party tools like FutureRestore that can help you do the same. You can also choose to dump your SHSH blobs in order to use them afterward. Though, in most of the cases, users have to jailbreak their device in order to do it.