Wait for the transfer to complete. DBI will automatically install the update and notify you when finished. Return to the Switch Home Menu. Highlight the Splatoon 3 icon. Press the (+) button to open Options.
Navigate to (or "NAND Install" if you prefer).
A Nintendo Switch running up-to-date Atmosphère . SPLTOON3-(USA)-NSwTcH-NSP-Update121-Ziperto.rar
Ensure your system firmware version is compatible with Update 1.2.1 (typically version 15.0.0 or higher is recommended for this specific update).
A reliable installer such as DBI , Tinfoil , or Awoo Installer . Wait for the transfer to complete
If prompted for a password, check the source site (Ziperto) as they frequently use their domain name as the default password.
This specific file is an Update , not the base game. You must have the base version of Splatoon 3 already installed for this to work. Highlight the Splatoon 3 icon
Once extracted, you should see an .nsp file. This is the actual update file.