iPadOS 9.3.1 (build 13E238) is an official Apple over-the-air update for the iPad Pro 12.9-inch (Cellular), released on 2016-03-31T16:54:29Z. The update package is 330.95 MB. This is a delta (partial) update that requires 9.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: fd6b56a94b831313a3ea575759614a04092946ac.zip.