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 675.9 MB. This is a delta (partial) update that requires 11.2.6 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 8f66b24461d78217159d0b9ec95614d827c0f99f.zip.