iOS 8.4.1 (build 12H321) is an official Apple over-the-air update for the iPhone 6, released on 2015-08-13T18:05:15Z. The update package is 542.51 MB. This is a delta (partial) update that requires 8.0.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: af2bf6cc5a32129ac9ce8762fe02f123e157dedc.zip.