Apple Has Made It Impossible to Downgrade From iOS 26

If you installed iOS 26 on your iPhone, it is now officially impossible to downgrade. Apple has stopped "signing" iOS 18.6.2, ...
PCMag on MSN

Make Sure You Really Want iOS 26. There's No Going Back to iOS 18

As it usually does after a new iOS release, Apple has stopped validating its older mobile OS. So, if you upgraded to iOS 26, ...
Engadget

Ready to download iOS 26? Make sure your iPhone is eligible for the free update first

Have you updated your iPhone to the new iOS 26 yet or are you holding off? It's been available to download since September 15 — here's how to install it if you haven't yet. The new OS was released ...