iPadOS 12.3 (build 16F5155a) is an official Apple over-the-air update for the iPad Pro 12.9-inch (WiFi), released on 2019-05-07T17:03:54Z. The update package is 365.92 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: f40d0831c11e422060f64747998e2e7e873197eb.zip.