After messing with this, I found two things that will mess up this tool. If it won't decrypt a file for you, make sure it's not one of these things.
1. Strange characters will mess it up. I saw this elsewhere where somebody talked about the ! character messing things up, but any strange character, like Japanese text, etc. will cause issue. Examples I had were ! in multiple games, é in a pokemon game name, and the roman numerals Ⅳ used instead of IV in street Fighter for some reason.
2. The second issue is less clear, but it affects mostly DLC, and anything with a lot of NCCH files. Internally, in the batch script, it takes all NCCH files, and combines them into a variable for creating the cia. If there are too many files, the batch variable hits a hidden 8191 character limit, and the command fails because it is cut off.
Fixing this is out of my league, but as a workaround, rename the file temporarily to a one character name. If a file still has too many NCCH files, this may not work, but for me, this fixed conversion issues for all 4 of the files I had issues with by renaming them to "a.cia" temporarily.
Lastly, I still have one cia that is giving me issues, but it seems to be an issue with "decrypt.exe", and likely can't be fixed easily. Still, I hope this helps some of those with issues.
1. Strange characters will mess it up. I saw this elsewhere where somebody talked about the ! character messing things up, but any strange character, like Japanese text, etc. will cause issue. Examples I had were ! in multiple games, é in a pokemon game name, and the roman numerals Ⅳ used instead of IV in street Fighter for some reason.
2. The second issue is less clear, but it affects mostly DLC, and anything with a lot of NCCH files. Internally, in the batch script, it takes all NCCH files, and combines them into a variable for creating the cia. If there are too many files, the batch variable hits a hidden 8191 character limit, and the command fails because it is cut off.
Fixing this is out of my league, but as a workaround, rename the file temporarily to a one character name. If a file still has too many NCCH files, this may not work, but for me, this fixed conversion issues for all 4 of the files I had issues with by renaming them to "a.cia" temporarily.
Lastly, I still have one cia that is giving me issues, but it seems to be an issue with "decrypt.exe", and likely can't be fixed easily. Still, I hope this helps some of those with issues.