The installation takes roughly 30–60 seconds. Once complete, a new icon will not appear on your home screen. Instead, the base game’s icon will now read "Ver. 1.2" in the bottom corner.
You likely have a mismatch between your base game region and the update region. Uninstall the old update via System Settings → Data Management → 3DS → Add-on Content , then install the World CIA. pokemon ultra sun update 12 3ds world cia
This refers to a common, reputable repository where users can download the necessary CIA files to update their games. The installation takes roughly 30–60 seconds
Select the CIA file and choose "Install and delete CIA" . This refers to a common, reputable repository where
Available for all versions, including World/Region-Free editions Primary Fixes and Changes
To install this update on a Nintendo 3DS or 2DS console, you must have custom firmware installed (Luma3DS and Boot9Strap). Method A: SD Card Transfer (Manual) Power off your console and eject the SD card. Insert the SD card into your PC.
Wait for the installation to complete, press A to confirm, and exit FBI.