Apple has officially ceased signing the iOS 26.6.2 system. Consequently, users who have upgraded to iOS 27 are now unable to downgrade to any version of iOS 26 via official channels. iOS 27 was rolled out to the public on September 15th and has been accessible for approximately a week. Although iOS 26.7 was also unveiled concurrently, it is only available as an OTA (Over-The-Air) update and does not come with a complete firmware file, making downgrading from iOS 27 unfeasible. When installing a new version of iOS, Apple conducts server-side verification. Only system versions with an active signing status, marked as 'Yes,' can successfully pass this verification and complete the installation process. This strategy is implemented to prevent users from reverting to older versions and to discourage the use of outdated systems that lack essential security updates. At present, users who have refrained from upgrading to iOS 27 can continue to utilize iOS 26.