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iOS 26.4 No Longer Signed by Apple, Blocking Downgrades From iOS 26.4.1
Apple today stopped signing iOS 26.4, so iPhone users who have updated to iOS 26.4.1 are no longer able to downgrade to the earlier version of iOS. iOS 26.4.1 came out a week ago. When software is "signed," it means it can pass the server-side verification check that Apple does when a user downloads a new version of iOS on an iPhone. An update that's not signed can't be installed because it won't pass the verification check.
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