If you are planning to downgrade from iOS 18.3.1 to iOS 18.3, you can no longer do that as Apple has stopped signing the older firmware.
Apple is No Longer Signing iOS 18.3 and iPadOS 18.3 for iPhone and iPad, Downgrade from 18.3.1 No Longer Possible
This is nothing out of the ordinary or surprising at all. Whenever Apple releases a new firmware update, the company stops signing the older one after a while.
For those who love to update their iPhone and iPad devices to the latest update whenever it comes out, this is not a problem at all. But those who want to downgrade to the older firmware for any reason should know that Apple has pulled the plug on iOS 18.3 and iPadOS 18.3.
If you are currently on iOS 18.3 and something goes wrong with your device, and you want to restore your device using Finder, you have to update to iOS 18.3.1.
I will urge you to download and install the latest software update on your iPhone and iPad whenever it becomes available. iOS 18.3.1 and iPadOS 18.3.1 are extremely important updates that not only fix bugs, but also patch crucial security issues as well.
In order to install the update right now, go to Settings > General > Software Update on your iPhone or iPad. Once here, tap on Update Now when the latest update shows up.
