For users operating within the 3DS homebrew world, file extensions matter immensely.
When you see it refers to a standalone update package packaged as a CIA file. Installing this file does not overwrite or delete your current save file; rather, it injects the patch into the 3DS title/0004000e/ directory, which the system automatically overlays whenever the base game launches. How to Install the Update on a Modded 3DS (Using FBI) pokemon ultra sun update 12 3ds world cia updated
Disclaimer: This report is for informational purposes regarding the technical specifications and history of the software update. The installation of Custom Firmware and the downloading of copyrighted files may violate Nintendo's Terms of Service. Users should exercise caution and ensure they own a legitimate copy of the software. For users operating within the 3DS homebrew world,
Pokémon Ultra Sun Update 1.2: The Ultimate 3DS CIA Installation Guide How to Install the Update on a Modded
If your game crashes immediately after installing the update, your Luma3DS firmware might be outdated, or the CIA file itself was corrupted during the download process. Update your Luma3DS boot files to the latest version and attempt a clean reinstall of the CIA.
Without this update, the game rejects any attempts to communicate with external custom networks or local multiplayer features, mandating that the core data matches version 1.2.