Can I Downgrade iPhone 3G?

iPhone 3G (iPhone1,2) - Front view

iPhone 3G

iPhone1,2

A1324
A1241
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Downgrade is Possible

Downgrade to iOS 4.1 is Currently Supported

Apple is currently signing multiple iOS versions simultaneously. This temporary signing window overlap allows you to restore your iPhone 3G to the older build(s) listed below using a computer without encountering verification errors.

iOS 4.1 8B117

September 3, 2010

Downgrade Target
Firmware History for iPhone 3G
iOS 4.2.1 8C148

November 18, 2010

Signed
iOS 4.1 8B117

September 3, 2010

Signed
iOS 4.0.2 8A400

August 9, 2010

Unsigned
iOS 4.0.1 8A306

July 13, 2010

Unsigned
iOS 4.0 8A293

June 17, 2010

Unsigned
iOS 3.1.3 7E18

January 22, 2010

Unsigned
iOS 3.1.2 7D11

October 5, 2009

Unsigned
iOS 3.1 7C144

September 3, 2009

Unsigned
Frequently Asked Questions

Can I downgrade from an iOS Beta on iPhone 3G?

Yes. If your iPhone 3G is running an iOS Beta, you can always restore back to the latest signed public release using Recovery Mode in Finder (Mac) or iTunes / Apple Devices (Windows).

Can I downgrade to the iOS version iPhone 3G originally shipped with?

No. Apple permanently closes the signing window for older releases. Even though iPhone 3G originally launched with an earlier version, Apple servers will no longer authenticate that installation.

What can I do if I cannot downgrade iPhone 3G but experience battery or performance bugs?

You can perform a clean restore to the latest signed firmware using a computer to eliminate software glitches and corrupted cache, or await the next minor point update from Apple that includes targeted bug fixes.

Can I downgrade iPhone 3G if the signing window has closed?

No. Apple servers reject restore verifications for unsigned builds (returning iTunes Error 3194). Unsigned firmware cannot be installed on standard Apple devices.

Will restoring or downgrading iPhone 3G erase data?

Yes. Flashing an IPSW firmware file requires a restore that wipes on-device storage. Ensure your personal data is backed up to iCloud before proceeding.