Apple перестала подписывать iOS 12.3, 12.3.1 и 12.3.2, а значит их больше нельзя установить. Теперь актуальная прошивка — iOS 12.4.
Apple stops signing iOS 12.3 and more following release of iOS 12.4 Apple today has stopped signing iOS 12.3, iOS 12.3.1, and iOS 12.3.2 following last week?s release of iOS 12.4. This prevents users from downgrading from iOS 12.4 to a previous version of iOS. Apple generally stops signing older releases of iOS within a few weeks of releasing an update to the public. iOS 12.4 was [?] 9to5mac.com
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