iPadOS 11.3.1 (build 15E302) is an official Apple over-the-air update for the iPad Pro 9.7-inch (WiFi), released on 2018-04-24T17:08:24Z. The update package is 590.8 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: 7bcd12bd94170f500b843f834c3d3effd7c705c1.zip.