Try reformatting the SD card then: https://dsi.cfw.guide/sd-card-setup.htmlThere says, The object inserted into the SD card slot is invalid.
I will try it, if it happens, thank you very muchTry reformatting the SD card then
If the issue persists, then the DSi's SD slot might be malfunctioning.
Probably your SD Adapter is dirty internally.There says, The object inserted into the SD card slot is invalid.