iOS 9.9.12.1 (build 16B5059d) is an official Apple over-the-air update for the iPhone 6+, released on 2018-09-18T17:20:21Z. The update package is 2.27 GB. This is a full OTA update that can be applied from any compatible base version. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 3c9ada515dacbc4902346f206989b323cd87cd69.zip.