iPadOS 8.4 (build 12H143) is an official Apple over-the-air update for the iPad mini 3 (WiFi), released on 2015-06-30T15:51:15Z. The update package is 725.45 MB. This is a delta (partial) update that requires 8.0.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 6b84d79a112de708a2dd55ef201c9c286cfaf5ff.zip.