iPadOS 12.3 (build 16F5148a) is an official Apple over-the-air update for the iPad Pro 3 (11-inch, Cellular, 1TB Model), released on 2019-04-29T17:35:56Z. The update package is 473.49 MB. This is a delta (partial) update that requires 12.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 5973cffa739f609121f5045a0c9304d0b97a46c6.zip.