Apple has stopped signing iOS 26.3.1 and iPadOS 26.3.1 updates, which means you can no longer downgrade from 26.4.
iOS 26.3.1 and iPadOS 26.3.1 Updates No Longer Being Signed, You Can No Longer Downgrade from the New 26.4 Update
iOS 26.3.1 and iPadOS 26.3.1 were being signed for quite some time, which means users were able to downgrade to it from the newly released 26.4 update without issues.
In fact, you could re-restore your iPhone or iPad on version 26.3.1 as many times as you liked. But now, you can no longer do that since Apple has stopped signing the older firmware.
You can manually avoid the new 26.4 update, if you like. Just head over to Settings > General > Software Update > Automatic Updates, and select Off.
However, I will urge everyone to go ahead and update to iOS 26.4 and iPadOS 26.4 immediately. It’s packed with loads of bug fixes and security enhancements, apart from new features.
You can update your iPhone and iPad by going to Settings > General > Software Update. When you see the new 26.4 update, just tap on Update Now. If you have 50% or more battery life remaining, the update will install immediately; otherwise, you’ll be asked to plug your device into a power outlet.
