iOS 11.3.1 (build 15E302) is an official Apple over-the-air update for the iPhone X (GSM), released on 2018-04-24T17:09:41Z. The update package is 47.24 MB. This is a delta (partial) update that requires 11.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: eb0cafe9081104bc9d5e571c93335b0fbb00dd1a.zip.