A few days after the release of iOS 11.4 with some new features like Messages in iCloud, AirPlay 2, etc. Apple stopped signing iOS 11.3.1.
In this regard, you will no longer be able to roll back or upgrade to iOS 11.3.1, and when you try, you will encounter the error 'Error 3194'.
The release of Electra jailbreak with support for iOS 11.3.1 is already on the horizon, so rollback would be very useful. In addition, some users prefer to roll back to a previous version if their device is not performing well due to an upgrade.
Unsurprisingly, Apple stopped signing iOS 11.3.1 so soon, as the company has been using this strategy for the past few years to limit jailbreak. The company not only releases new versions with fixes for bugs and vulnerabilities used by the jailbreak, but also stops signing files of old versions so that users cannot rollback.
We hope you managed to take advantage of the opportunity to roll back to iOS 11.3.1 and be able to install the Electra jailbreak update for iOS 11.3.1 on your device.
If you saved the files iOS 11.3.1 SHSH blobs, you can still rollback to iOS 11.3.1 via futurerestore. However, in this case, Touch ID or Face ID may stop working.
Coolstar is already working on jailbreak iOS 11.3.1 Electra after Ian Beer released his new exploit.