iOS & iPadOS Signing Status
Check if your iOS & iPadOS IPSW firmware version is still signed by Apple. Verify signing status before restore, update, or downgrade.
Apple is currently signing 14 iOS and 12 iPadOS releases, newest iOS 27.0.1 and iPadOS 27.0.1. Every entry below is checked against Apple's signing servers, newest first.
Apple only allows installation of firmware versions they currently "sign." Once a version is unsigned, you can no longer install it—even if you have the file.
Apple typically signs the latest version and occasionally one older release. Older versions stop being signed shortly after new updates.