iOS 11.3.1 (build 15E302) is an official Apple over-the-air update for the iPhone X (Global), released on 2018-04-24T17:09:30Z. The update package is 681.36 MB. This is a delta (partial) update that requires 11.2.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 75e09b538f679d172eb4968c395f7c49172c8b5c.zip.