Apple officially ended the signing of iOS 18.0 today, effectively preventing iPhone users from downgrading their devices to the software version.
iOS 18.0.1 debuted one week ago, which prompted Apple to stop iOS 18 from being signed. The Cupertino-based company routinely stops older versions from being accessed a week or so after the newer software update launches. With this in mind, iPhone users can no longer install iOS 18 on their devices as a software verification check is done server-side. The reason why Apple stops downgrading is to encourage users to get up-to-date software, which has the latest security patches. It’s worth noting that iPhone 15 users can downgrade to iOS 17.7, which has not been stopped yet.

The latest update, iOS 18.0.1, contains fixes for problems affecting the Messages app, as well as the Camera app. Touch screen fixes were also implemented, and two vulnerabilities were patched.