Safely remove the SD card and back up every single file to a secure directory on your computer.
The error code is a precise, technical notification that your device's storage is out of space. According to the official 3dbrew technical specifications for the Nintendo 3DS's Filesystem Services (PXI), the error's decrypted meaning is unequivocal: "Failed to write file. Partition is full." . Other community-driven sources confirm it as a "Descartition full" [sic] or partition full error. 0xc86044d2 full
The hex code is a critical system error code generated by Nintendo 3DS homebrew software—most notably the FBI open-source title manager. It explicitly means "Partition Full," indicating that your console's SD card does not have enough unallocated storage space to complete a .cia (CTR Import Archive) file installation. Safely remove the SD card and back up