Guides
Ryujinx RYU-0001 / 0002 / 0003 Errors: Keys Not Found, Firmware Parsing Error, MissingKeyException (2026)
Key points
- RYU-0001: prod.keys not found. RYU-0002: no firmware installed. RYU-0003: firmware can't be parsed, usually because keys are older than the firmware. RYU-0004: no game at that path.
- For RYU-0001, check that prod.keys is in the system folder inside the Ryujinx folder and named exactly prod.keys. If it still fails, the keys file itself is bad and needs a fresh dump.
- For RYU-0003, use keys and firmware from the same version. Keys must never be older than the firmware.
- MissingKeyException (Missing NCA title key and friends) and KeyNotFoundException 'None' in the log mean missing or outdated keys. Update prod.keys and title.keys.
- Some late-2026 games built with SDK 22.2 use new ZBIC compression that Ryubing can't read yet (as of 2026-11-01). That isn't a keys problem. Eden Nightly already supports it.
- Kenji-NX's desktop build uses the same RYU codes and the same fixes.
On this page
RYU-XXXX codes come from the setup check that Ryubing (the community continuation of Ryujinx) runs at startup and before a game opens. RYU-0001 means prod.keys wasn't found. RYU-0002 means no firmware is installed. RYU-0003 means the firmware couldn't be parsed, usually because your keys are older than the firmware. RYU-0004 means there's no game at the given path. The usual fix: put prod.keys in the system subfolder of the Ryujinx folder, keep the name prod.keys, and use keys and firmware from the same version. The desktop build of Kenji-NX uses the same codes. As of November 2026 there's also a case where the keys are fine and the game still won't open: some late-2026 games use a new compression format Ryubing can't read yet. See the last section.
What the error looks like
Ryujinx Error (RYU-0001)
RYU-0001: Keys not found.
Ryujinx was unable to find your "prod.keys" file.
For more information on how to fix this error, follow our Setup Guide.
Per Ryubing's source, the part after RYU- is the error number in four hex digits.
Error code cheat sheet
| Code | Message | When it shows | Cause | Fix |
|---|---|---|---|---|
| RYU-0001 | Keys not found. / Ryujinx was unable to find your "prod.keys" file. | At startup or when installing firmware | No prod.keys, wrong folder, wrong file name, or invalid keys | Put it in the system folder and restart; if it still fails, re-dump the keys |
| RYU-0002 | Firmware not found / Ryujinx was unable to find any firmwares installed. | When opening a retail game (.nro / .nso homebrew skips the check) | No firmware installed | Actions → Install Firmware |
| RYU-0003 | Firmware parsing error / Ryujinx was unable to parse the provided firmware. This is usually caused by outdated keys. | When installing firmware | Keys older than the firmware | Use keys and firmware from the same version |
| RYU-0004 | Application not found / Ryujinx couldn't find a valid application at the given path. | When opening a game from a shortcut or the command line | File moved, renamed, or the drive letter changed | Re-add the game folder and recreate the shortcut |
| RYU-DEAD | Unknown error / An unknown error occured! | Anytime | Uncategorized error | Read the log (below) |
RYU-0001: Keys not found
Ryubing looks for prod.keys in the system folder of its data directory. Check in this order:
- Location. Open File → Open Ryujinx Folder, go into the
systemsubfolder, and put prod.keys there (plus title.keys if you have it). The default data folder on Windows is%appdata%\Ryujinx. - File name. It must be exactly
prod.keys. Windows hides extensions by default, so the file may really beprod.keys.txt. Saving twice in a browser can produceprod(1).keys. - Restart. Fully close Ryubing and reopen it. It only re-checks at startup.
- Menu install. Newer Ryubing builds have Actions → Install Keys, which takes a
.keysfile or a folder. If it saysAn invalid Keys file was found in ..., the file's contents are invalid. - Still failing with the file in place. The keys file itself is the problem: incomplete, corrupted, or not prod.keys. In Ryubing issue #405 a user installed keys, then got RYU-0001 while installing firmware. The collaborator's answer was to re-dump the keys from their own Switch.
RYU-0002: Firmware not found
Ryubing checks for firmware before it opens a retail game and shows RYU-0002 if there is none. Homebrew (.nro / .nso) skips this check.
- Use Actions → Install Firmware → XCI or ZIP... and pick the firmware ZIP, or Folder... to install from a folder. Some builds put this under the Tools menu. Once installed, the system version shows in the bottom right.
- If the file isn't firmware, you'll see
A valid system firmware was not found in .... - If you open an untrimmed cartridge XCI, Ryubing asks
Would you like to install the firmware embedded in this game?Say yes and it uses the firmware inside the cartridge image.
RYU-0003: Firmware parsing error
The message already names the cause: your keys are older than the firmware. Firmware is decrypted with prod.keys, and old keys lack the key generation newer firmware needs.
- Fix: use keys and firmware from the same version. Keys must be at least as new as the firmware. After a console system update, dump both again.
- Same version and still RYU-0003: there's no official explanation. Update Ryubing to the latest build, re-dump the keys and install again.
- Newer firmware isn't always better, since emulator support lags behind. See prod.keys, title.keys and firmware explained.
RYU-0004: Application not found
The path a shortcut or command line points to has no game file. Usually the file was moved or renamed, or an external drive got a new letter. Re-add the game folder, then open the game from the list or recreate the shortcut.
Log errors: when a game crashes or hangs
Many keys and firmware problems don't show a RYU dialog. The game just closes. Ryubing's FAQ says to open File → Open Logs Folder, pick the newest and largest log, and search for these lines.
| Log text (key part) | Meaning | Fix |
|---|---|---|
LibHac.Common.Keys.MissingKeyException: Missing NCA title key. | Title key for this game, update or DLC is missing, or keys are too old | Re-dump and update prod.keys and title.keys |
MissingKeyException: Unable to decrypt title key. | Same | Same |
MissingKeyException: Unable to decrypt NCA section. | Same | Same |
System.Collections.Generic.KeyNotFoundException: The given key 'None' was not present in the dictionary. | Listed as a keys problem in the official FAQ | Same |
System.IO.FileNotFoundException: System archive with titleid 0100000000000823 was not found on Storage BuiltInSystem. | Firmware too old; the system archive the game needs isn't there (the titleid varies) | Update keys and firmware together |
Ryujinx has encountered an error: System update title was not found in the firmware package. | The file you picked isn't firmware | Pick the firmware ZIP or an untrimmed cartridge XCI |
System.ArgumentException: An item with the same key has already been added. (settings won't open, or a crash) | Leftovers in the firmware registration folder; if the error mentions PTC, the PPTC cache is broken | Clear bis\system\Contents\registered in the Ryujinx folder and reinstall firmware; for PTC, right-click the game → Cache Management → Queue PPTC Rebuild |
Loader LoadNca: No ExeFS found in NCA (hangs on boot) | The game file was dumped the wrong way | Dump the game file again |
NPDM file not found, using default values! … Unable to load: Could not find Main NCA | You opened an update as if it were the game | Open the base game; add the update with right-click → Manage Updates |
Dialog: No applications found in selected file. | The file has no base game (an update, DLC or incomplete file) | Open the base game; add updates and DLC with Manage Updates / Manage DLC |
For how keys and firmware fit together and where each file goes, see prod.keys, title.keys and firmware explained. For crashes and black screens that aren't caused by keys, see troubleshooting.
Keys are fine, game still won't open: late-2026 releases
As of November 1, 2026, Ryubing has two known problems with new games. New keys or firmware won't fix either one.
| Log text | What it is | Status |
|---|---|---|
System.ArgumentOutOfRangeException: srcOffset ('-38731') … Lz4.Decompress … NsoReader.ReadSegmentImpl | Games built with SDK 22.2 compress their main program with the new ZBIC format (a Zstandard variant). Ryubing still tries LZ4, so the game fails right away | Ryubing issue #492 (2026-09-01, reported on Canary 1.3.351 with firmware 22.1.0), open |
GuestBrokeExecutionException with TlsHeapCentral::LockMutexSlow_ in the guest stack | The same SDK 22.2.0 games abort while the sdk module initializes | Ryubing issue #493 (2026-09-01), open |
If you see either one, try a Nightly build of Eden. Eden added ZBIC decompression (Switch 22.0+) in a 2026-09-27 commit. The stable v0.2.1 (2026-06-01) doesn't have it. For Eden's own errors, see the Error while loading ROM (0007) code list.
Kenji-NX and MeloNX
- Kenji-NX uses the same error dialog code as Ryubing on desktop, so it shows
RYU-XXXXand every fix here applies. We haven't verified the error text in Kenji-NX for Android. - MeloNX was rebuilt on Ryubing in 2.4, so mismatched keys and firmware break it the same way. On iPhone, though, you see MeloNX's own messages. See MeloNX errors.
FAQ
How do I fix Ryujinx error RYU-0001 Keys not found?
RYU-0001 means Ryubing can't find prod.keys. Open File → Open Ryujinx Folder, put prod.keys (and title.keys) in the system subfolder, make sure the file is named exactly prod.keys, and restart the emulator. You can also use Actions → Install Keys. If it still fails with the file in place, the keys file is invalid and needs to be dumped again from your console.
I already installed prod.keys. Why does installing firmware still show RYU-0001?
This exact case is Ryubing issue #405: keys installed, then firmware install still returned RYU-0001. The collaborator's answer was to re-dump the keys from your own Switch. Also check the file name. Windows hides extensions by default, so the file may really be prod.keys.txt or prod(1).keys.
What causes RYU-0003 Firmware parsing error?
Ryubing's own message says it: 'This is usually caused by outdated keys.' Your keys are older than the firmware. Use keys and firmware from the same version; keys must be at least as new as the firmware. If the versions already match, there's no official explanation. Update Ryubing to the latest build, re-dump the keys and install again.
How do I fix RYU-0002 Firmware not found?
Ryubing checks for firmware before it opens a retail game. Install it with Actions → Install Firmware → XCI or ZIP and pick the firmware ZIP. The system version then shows in the bottom right. If you open an untrimmed cartridge XCI, Ryubing offers to install the firmware embedded in the game. Say yes.
What does MissingKeyException: Missing NCA title key mean?
The title key for this game, update or DLC is missing, or your keys are too old. Ryubing's FAQ groups it with Unable to decrypt title key, Unable to decrypt NCA section and KeyNotFoundException 'None'. The fix for all of them is to re-dump and update prod.keys and title.keys.
Ryujinx says No applications found in selected file. What now?
The file has no base game in it. Usually it's an update or DLC opened as if it were the game, or an incomplete file. Open the base game, then add updates with right-click → Manage Updates and DLC with Manage DLC.
A new 2026 game crashes instantly in Ryubing even with new keys and firmware. Why?
Check the log for ArgumentOutOfRangeException: srcOffset together with Lz4.Decompress and NsoReader. That's the new SDK's ZBIC compression (Ryubing issue #492, still open on 2026-11-01). New keys won't help. Eden Nightly already supports ZBIC.
Does Kenji-NX show RYU error codes too?
Yes. Kenji-NX is a Ryujinx fork, and its desktop error dialog uses the same code, so it shows RYU-XXXX and the fixes are the same. We haven't verified the error text in Kenji-NX for Android.
Sources
- Ryubing Docs — FAQ & Troubleshooting (Common Errors and Troubleshooting)
- Ryubing Docs — Setup & Configuration Guide
- Ryubing issue #405 — RYU-0001 when installing firmware after installing prod.keys (2026-05-04)
- Ryubing issue #492 — NSOs with ZBIC compression fail to load (2026-09-01)
- Ryubing issue #493 — SDK 22.2.0 titles abort during sdk module init (2026-09-01)