Apple today stopped signing iOS 18.0.1, preventing iPhone users who have upgraded to iOS 18.1 from downgrading to iOS 18. Apple released iOS 18.1 a week ago on October 28.
It is not unusual for Apple to stop signing older versions of iOS shortly after a new version of iOS is released. When Apple stops signing an update, it can no longer be installed on an iPhone due to a server-side software verification check that happens before new software is installed, so those who have upgraded to the latest version of iOS 18 cannot downgrade to iOS 18.0.1.
Apple prevents downgrading to older versions of iOS to encourage iPhone users to keep their operating systems up to date with the latest security fixes.
The iOS 18.1 update added the first Apple Intelligence features, including Writing Tools, a new look for Siri, summaries and smart replies, and more. Apple CEO Tim Cook recently said that iPhone users are upgrading to iOS 18.1 twice as fast as iOS 17.1 during
