Apple has officially stopped signing iOS 26.6.2. iPhone users who have already upgraded to iOS 27, released on September 15, 2026, can no longer roll back to the previous major release. The change was first spotted by user Aaron Perris on X, as reported by outlets including 9to5mac.com.
Server-Side Signing Blocks Older Versions
Code signing is a security mechanism implemented by Apple: whenever an iPhone is restored or updated, the device contacts Apple’s servers to verify whether the respective firmware version is still officially authorized and digitally signed. If this signature is missing, the installation will fail. Users cannot bypass this barrier by downloading the corresponding iOS 26.6.2 firmware file (IPSW file) manually from the web and attempting to restore or flash it via a computer.
This procedure is routine for Apple. To patch known security vulnerabilities across as many devices as possible and ensure users stay on the latest version, the company regularly stops signing older releases shortly after rolling out a major system update.
Fallback Route via iOS 26.7 Also Blocked
For users running into post-update issues such as increased battery drain on iOS 27 or other teething problems, the path backwards is now permanently closed. Downgrading to iOS 26.7, which debuted on September 14, 2026, is not an option either: while Apple released iOS 26.7 for older systems, the iPhone build was distributed exclusively as a direct over-the-air (OTA) update. A standalone restore image (IPSW) was not provided for iPhones, unlike iPadOS 26.7.
iOS 26.6.2 was deployed only recently on September 8, 2026, carrying build number 23G90 to fix issues with software updates failing to download over cellular networks. Besides users unhappy with iOS 27, the signing halt primarily impacts the jailbreak community and security researchers, who often rely on older software builds for testing purposes.
What Users Need to Know Now
Those still running iOS 26 and hesitating to upgrade can remain on their current system for now and install security updates such as iOS 26.7 via OTA. However, once a device is updated to iOS 27, there is no going back. Affected users grappling with software bugs after updating—such as system component glitches under iOS 27—cannot downgrade to older versions and will have to wait for upcoming bug fixes from Apple.
Sources: Borncity.com
