Moving saves from emuMMC to sysNAND with JKSV is one of the most requested workflows, and also one that needs the most honesty about risk. This guide describes the community workflow, why sysNAND requires extra caution, and how to reduce — not eliminate — the chance of problems if you decide to proceed.
Why this transfer is sensitive
emuMMC and sysNAND are separate environments. Saves created or modified in emuMMC, especially while offline with homebrew, may not be considered clean by Nintendo if they later appear on a sysNAND that connects to online services. There is no method that guarantees a sysNAND will be treated as untouched after homebrew use, and JKSV does not promise ban protection.
In most reported cases, users who attempt this transfer do so entirely offline and accept that any sysNAND that has run CFW or received transferred homebrew-managed saves carries uncertainty. If keeping a pristine online sysNAND matters to you, the safest choice is not to perform this transfer at all. Read this whole section before you decide.
The general workflow
The basic idea is simple: back up the saves while booted into emuMMC, then restore those backups while booted into sysNAND with CFW, using the same JKSV backup files stored in /JKSV/ on the SD card. Because both environments can share the same SD card and the same /JKSV/ folder, the files themselves usually do not need to be moved by hand.
- Boot into emuMMC, launch JKSV with Title Override, and back up the titles you want to move.
- Copy the /JKSV/ folder to a PC as an extra safety copy.
- Reboot into sysNAND with Atmosphère, launch JKSV the same way, and confirm the backups are listed.
- Restore each backup to the matching user and title on sysNAND.
Match users and titles exactly
The user profile and title must correspond between the two environments. If the sysNAND profile is a different account or the game is not present in a compatible state, the restored save may not be recognised. Where needed, JKSV can create save data for a title without launching the game first, which can help prepare the destination before a restore.
Restore one title first and test it in the game before doing the rest. A single tested restore validates that your users, titles, and backup files line up. Batch-restoring everything and only then discovering a mismatch wastes time and makes diagnosis harder.
Reduce risk where you can
Work offline throughout the transfer. Do not connect the sysNAND to online services during the process, and think carefully before connecting afterwards with transferred saves present, particularly for online games. Saves for offline, single-player titles are generally discussed differently in the community from saves for competitive online titles, but neither category comes with a guarantee.
Keep your emuMMC backups untouched as the source of truth until you have confirmed the sysNAND copies work. If anything goes wrong, you can return to emuMMC and try again rather than having modified your only copy.
What this guide cannot promise
No guide can promise that a transfer is undetectable or ban-proof. Nintendo’s enforcement decisions are not published in detail, and community experience is anecdotal and changes over time. This guide describes the mechanics and the commonly discussed precautions with that uncertainty stated plainly, so you can make an informed decision rather than relying on a false assurance.
Next steps and related guides
This guide is part of our hub collection. Before you start, get the current build from the download page. You may also find these guides useful: transfer saves between consoles and JKSV safety and ban risk guide.
JKSV is JK’s Save Manager by developer J-D-K, released under GPL-3.0 for Nintendo Switch 1 with Atmosphère. The current release is the date-based tag 12/02/2025. Always keep a second copy of important backups on your PC or in cloud storage, and test a restore on a non-critical save before you rely on a backup for a game you care about.