iPadOS 11.3.1 (build 15E302) is an official Apple over-the-air update for the iPad Pro 12.9-inch (Cellular), released on 2018-04-24T17:08:53Z. The update package is 585.24 MB. This is a delta (partial) update that requires 11.2.5 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 7f81f8aa66000f0111582ebdeeb9b5aafe8956d0.zip.