If you are using a standard file-browser method within homebrew: Navigate to the sdmc:/ (SD Card) directory. Open your NSPs folder.
If the updated NSP fails to launch or install, your Switch may need updated sigpatches to run unofficial software.
Place the Dr. Kawashima Update NSP file onto your Switch SD card (e.g., in a folder named updates ).
Boot your Nintendo Switch into your preferred CFW environment.
What your Switch is currently running?