iOS 11.3.1 (build 15E302) is an official Apple over-the-air update for the iPhone 8 Plus (Global), released on 2018-04-24T17:09:26Z. The update package is 859.52 MB. This is a delta (partial) update that requires 11.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 538a942af660cd02b6065a2ce784f115f33ec4ad.zip.