A: This error is caused by twlnf. It has a critical bug that doesn’t properly update the entire NAND after modifying it. This causes certain homebrew (like the Unlaunch installer) to throw an error. Fortunately, this is fixable. Unfortunately, the method to fix it isn’t set in stone, and largely varies from system to system. Generally, deleting any DSiWare installed via twlnf in the past does the job, but make sure you have another homebrew entrypoint available if you delete an entrypoint. It has also been reported that moving all DSiWare to the SD card and back to the system can help in some cases.
A: No, you will need a hardmod to install HiyaCFW. Follow Gadorach’s hardmodding guide to hardmod your DSi. Previous soldering experience is required.
A: Yes, using DSiMenu++. See the Replacing System Menu with DSiMenu++ page for more information. Low-level “full” formatting your SD card with a tool like GUIFormat can help as well, but this will not get you around the DSi Menu’s block limit, whereas DSiMenu++ does.
A: While in the DSi System Menu, move to the DSi Camera app, take out the SD card, then launch the DSi Camera app. If you’re in the app, then you’re in SysNAND. If not, then something went wrong when trying to install DSiMenu++.
A: Unfortunately, not at this time. Ideally there would be a tool, or an update to the Unlaunch installer itself, that allows for a direct uninstallation. Currently no such tool exists. Until one exists, all methods of installing Unlaunch either require unsafe tools like twlnf, or restoring a NAND backup. Uninstalling via twlnf would trigger twlnf’s NAND update bug, breaking the option to install unlaunch in the future, and NAND backups are not only dangerous but is also very stressful on the DSi’s components.
A: This can happen for several reasons, but the most common is that your PC is missing Windows Updates that are required for the program to run.
If fuse-3ds shows nothing but a black command prompt screen, just wait a while longer- the program can be slow to start.
If fuse-3ds shows the following error at startup:
The procedure entry point ucrtbase.terminate could not be located in the dynamic link library api-ms-win-crt-runtime-l1-1-0.dll.
You are missing the following Windows Update: https://support.microsoft.com/en-us/help/2999226/update-for-universal-c-runtime-in-windows
If fuse-3ds fails to mount with the error message:
Cannot create WinFsp-FUSE file system: unspecified error.
You are missing the following Windows Update: https://technet.microsoft.com/en-us/library/security/3033929.aspx
Both of these updates are several years old. If you’re missing them, it is highly recommended that you enable Windows Update on your machine in order to keep your system updated and secure, and to avoid issues like this in the future.