iOS 4.2.1 (8C148) for iPhone 4 (GSM)

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iPhone 4 (GSM)

✗ This firmware is not signed. This means you cannot restore to it in Finder, the Apple Devices app, iTunes, or idevicerestore.

Your download should begin shortly. If it does not, you can download it directly here:

Download (624 MiB)

This firmware is not signed. This means you cannot restore to it in Finder, the Apple Devices app, iTunes, or idevicerestore. The instructions below are included for reference only.

Windows

  1. Install the latest version of Apple Devices from the Microsoft Store.
  2. Plug your iPhone 4 (GSM) in to your PC.
  3. Open Apple Devices, and navigate to your iPhone 4 (GSM).
  4. Hold the Shift key on your keyboard, and press "Restore".
  5. Select the iPhone3,1_4.2.1_8C148_Restore.ipsw file that you downloaded.
  6. Wait for the restore to complete, and the iPhone 4 (GSM) to reboot.

macOS

  1. Plug your iPhone 4 (GSM) in to your Mac.
  2. Navigate to your iPhone 4 (GSM) in Finder.
  3. Hold the Option or Alt key on your keyboard, and press "Restore".
  4. Select the iPhone3,1_4.2.1_8C148_Restore.ipsw file that you downloaded.
  5. Wait for the restore to complete, and the iPhone 4 (GSM) to reboot.

Linux

  1. Install idevicerestore.
  2. Plug your iPhone 4 (GSM) in to your PC.
  3. Open a terminal, and navigate to the IPSW file that you downloaded, e.g. cd ~/Downloads
  4. To perform a full erase restore, type idevicerestore -e iPhone3,1_4.2.1_8C148_Restore.ipsw and press enter.
  5. Wait for the restore to complete, and the iPhone 4 (GSM) to reboot.

Windows

  1. Open PowerShell, and navigate to the IPSW file that you downloaded, e.g. cd Downloads
  2. Type Get-FileHash iPhone3,1_4.2.1_8C148_Restore.ipsw -Algorithm SHA1
  3. The output of the command should match the following checksum: b8b485c111fc25515487dbada0f2e630b66ccdb1. If it doesn't, you may need to redownload the file.

macOS

  1. Open a terminal, and navigate to the IPSW file that you downloaded, e.g. cd ~/Downloads
  2. Type openssl sha1 iPhone3,1_4.2.1_8C148_Restore.ipsw
  3. The output of the command should match the following checksum: b8b485c111fc25515487dbada0f2e630b66ccdb1. If it doesn't, you may need to redownload the file.

Linux

  1. Open a terminal, and navigate to the IPSW file that you downloaded, e.g. cd ~/Downloads
  2. Type openssl sha1 iPhone3,1_4.2.1_8C148_Restore.ipsw
  3. The output of the command should match the following checksum: b8b485c111fc25515487dbada0f2e630b66ccdb1. If it doesn't, you may need to redownload the file.

Checksums

SHA1sumb8b485c111fc25515487dbada0f2e630b66ccdb1
Please note, the documentation below is supplied from Apple's update servers. We don't modify the contents of this documentation.

iOS 4.2 Software Update

This update contains improvements, including the following:

• AirPrint

    - Print mail, photos, web pages, and more directly to

          AirPrint compatible printers on a local wireless network

• AirPlay

    - Wirelessly stream videos, music, and photos to

          Apple TV

    - Wirelessly stream music to AirPlay compatible speakers

          and receivers, including AirPort Express

• FaceTime improvements

    - Initiate calls with Voice Control

    - Initiate calls from an SMS conversation

    - Support for Bluetooth accessories

• Find text on the web page in Safari

• New fonts setting available for Notes

• New SMS/MMS text tones and the ability to set custom

      tones per contact

• Additional restrictions (parental controls) available:

    - Account settings

    - App deletion

    - Game Center friends

    - Location settings

• Ability to import .ics files into Calendar

• Bug fixes, including:

    - Eliminates sound artifacts occasionally captured in

          recorded audio with 4th generation iPod touch

    - Improves audio playback to car stereos via USB

Products compatible with this software update:

• iPhone 4

• iPhone 3GS

• iPhone 3G

• iPod touch 2nd generation or later

Not all improvements apply to all models. For more information, go to:

http://www.apple.com/ipodtouch/software-update/

http://www.apple.com/iphone/software-update/

For feature descriptions and complete instructions, see the user guides for iPhone and iPod touch at:

http://support.apple.com/manuals/iphone

http://support.apple.com/manuals/ipodtouch

For more information about iPhone and iPod touch, go to:

http://www.apple.com/iphone

http://www.apple.com/ipodtouch

To troubleshoot your iPhone or iPod touch, or to view additional support information go to:

http://www.apple.com/support/iphone

http://www.apple.com/support/ipodtouch

For information on the security content of this update, please visit this website:

http://support.apple.com/kb/HT1222

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