iPadOS 11.2.1 (build 15C153) is an official Apple over-the-air update for the iPad mini 3 (China), released on 2017-12-13T18:06:59Z. The update package is 355.49 MB. This is a delta (partial) update that requires 11.1.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 30d5e1755d6907baad5e32de0160e0a95149b4d7.zip.