Snaketocopter

Figured it out. In manage emulators, I had to rename Super Nintendo Entertainment System to Nintendo SNES. I had changed the system name for a more uniform look in the list on the left side, but I guess I needed to change it in the command line settings too

The Roms are in the end format. I'm assuming they don't need to be extracted. I've tried running it with the extract Roms before running box checked and unchecked and still no go. If nothing else I can use a different emulator for snes. It just would have been more convenient to use RetroArch.

The snes9x next core hasn't given me any compatibility issues and works fine when running RetroArch alone. However, I also downloaded both of the cores you listed(and made the appropriate command line edits for the emulator in Launchbox) and for each one I still got the same error.

Was this problem ever resolved? I'm having the same issue with the snes9x_next_lbretro core. All of the runtimes and software are correct/updated. All the other RetroArch cores work in Launchbox and the SNES games run fine if I use RetroArch without LB. Kinda stumped as to why thisnis happening and any help would be appreciated.