Thanks very much for the reply man I appreciate it, but it doesn't look like it worked. I used "hactool keyset=" as well as "hactool --keyset=" but neither seemed to set correctly. I've got a directory in my %userprofile% now, and although prod.keys is in there (and contains all the same keys from keys.txt exactly as they were output from the keys.py script, 40 keys in total) but it's still erroring out with "Invalid NCA Header" when I try to load an NCA. Could it be something wrong with keys.txt itself? Looking at other replies, it seems I've got all the right keys in there.