iOS 8.4 (build 12H143) is an official Apple over-the-air update for the iPhone 6+, released on 2015-06-30T15:51:23Z. The update package is 621.16 MB. This is a delta (partial) update that requires 8.1.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: e1423bede3ad78f02273ce3dcfb40d6a1f34b54f.zip.