Last verified: {{VERIFY: DD Month 2026}}
IPSW signing is Apple’s check that only lets a device install firmware Apple has cryptographically approved for that exact model. When you restore or update, your iPhone contacts Apple’s signing server (TSS) to confirm the file is currently signed — if it isn’t, the install fails with an error like “This iPhone software is not currently signed.” Apple typically signs only the newest release (plus sometimes the prior one briefly), which is why you usually can’t downgrade once a new version ships. Signing status changes without notice, so always check before attempting a downgrade or older restore.
Before you start
- Back up first. Follow Apple’s official backup guide — signing status can close mid-restore attempt, and you don’t want to be mid-process without a backup.
- Find My must be off if you plan to restore rather than update. Settings → [your name] → Find My → Find My iPhone → off.
- Cable and computer. A genuine or MFi-certified cable and a Mac or Windows PC with Finder, Apple Devices, or iTunes.
What signing actually checks
Every time you restore or update via Finder, the Apple Devices app, or iTunes, three things happen:
- Your device sends the IPSW file’s signature and your device’s unique identifiers to Apple’s TSS (Tatsu Signing Server).
- Apple checks whether that specific build is still in its signing window for your exact model.
- If signed, Apple returns an authorization ticket (SHSH) and the install proceeds. If not, the install is rejected before it writes anything to the device.
This is why the check happens online — there is no way to force an install of an unsigned build without a saved authorization ticket (see SHSH2 blobs explained for what that does and doesn’t make possible).
Why Apple closes the signing window
Apple stops signing older builds shortly after a new release to:
- Push users onto the version with the latest security patches
- Reduce support burden across many parallel firmware versions
- Close known exploits that some older builds left open
The window usually closes within one to a few weeks of the next release, though Apple doesn’t publish an exact timetable — treat any downgrade window as temporary and act quickly if you need it.
How to check current signing status
There’s no official Apple dashboard for this. In practice:
- Try the update/restore in Finder or Apple Devices — if the specific build is unsigned, you’ll get the “not currently signed” error immediately, before any data is touched.
- Community-run tracking sites are commonly used to check signing windows, but treat any status they report as unconfirmed until you test it yourself in Finder or Apple Devices — Apple can close a window without notice.
Check your model’s current firmware directly on the iPhone firmware hub before attempting any restore.
If it doesn’t work
- “This iPhone software is not currently signed.” The build you’re trying to install has closed. Only the current version (visible on the iOS 27 IPSW download page) will pass. See the full restore error code index for related errors.
- Signing check hangs indefinitely. Usually a network/firewall issue blocking Apple’s signing servers — try a different network or disable VPN.
- Downgrade worked yesterday, fails today. The signing window closed between attempts — this is expected and not a bug on your end.
- Error appears only on some Wi-Fi networks. Corporate or school networks sometimes block Apple’s signing-server ports; try cellular or a home network.
Frequently asked questions
How do I know if Apple is still signing an older iOS version?
Attempt the restore in Finder or the Apple Devices app — if the build is unsigned, you’ll see “This iPhone software is not currently signed” immediately, before any data changes. There’s no official public dashboard, so treat any third-party status tracker as unconfirmed until tested.
Can I bypass IPSW signing to install an older version?
Only if you saved a SHSH2 blob for that exact device and build while it was still signed, and even then it requires additional tools beyond Finder or iTunes. See SHSH2 blobs explained for what’s realistically possible.
Why did my downgrade work last week but fail today?
Apple closed the signing window for that build in between. Signing windows typically last days to a few weeks after a new release and can close without warning.
Does signing status affect updating to a newer version?
No — the current release is always signed, so updating forward never triggers a signing error. Signing only blocks going to an older or otherwise unsigned build.
Is IPSW signing the same thing as jailbreak detection?
No. Signing is Apple’s standard authorization check for any install, jailbroken or not. It exists independently of jailbreaking and applies to every iPhone, iPad, and Mac restore.
Do beta versions have separate signing windows?
Yes — Apple manages beta and public release signing windows separately, and betas are usually unsigned much sooner after the next beta or the public release ships.
This site is not affiliated with, endorsed by, or sponsored by Apple Inc. All firmware download links resolve to Apple’s official servers — we do not host, mirror, or distribute firmware files.
