iOS 11.3.1 (build 15E302) is an official Apple over-the-air update for the iPhone 8 Plus (GSM), released on 2018-04-24T17:09:39Z. The update package is 750.82 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: d4b50dc6ede07037ff6b4335e772cf7ef015fd7b.zip.