certain FDS files straight up don't open

[StickyChannel92]

FCEUX is an NES/Famicom emulator. I tried loading a Famicom Disk Game, it rebooted instead of loading.

On Retroarch, I installed the FCEUmm core, but when I tried to launch the FDS file, instead of allowing me to pick which core to use, it does the exact same thing: crash and reboot.

Why is this happening?
The game I'm using: Apple Town Story

[jSTE0]

On Retroarch, I installed the FCEUmm core

Do you have disksys.rom in the RetroArch system directory? See here for the correct checksum.
Same applies to FCEUX, that file needs to be in .fceux.

[jSTE0]

Where do I put my disksys.rom if loading mesen_libretro.so in RetroArch?

There's no mesen core for Miyoo. If you mean the PC version, check the documentation for that.

[StickyChannel92]

Which core works best for the mentioned game, then? FCEUX crashes when playing this game, either on computer or Miyoo.

[jSTE0]

The only core that can emulate FDS is FCEUMM. If that game doesn't work on the PC either, please report it upstream.
Same applies to FCEUX, though the PC version is much newer than the version for Miyoo.

[StickyChannel92]

The game doesn't work with FCEUMM. Retroarch crashes when loading it and goes back to the PocketGo main menu, and on PC, the game crashes, too on PC.

Same thing with FCEUX, even the latest version on github.com/TASEmulators/fceux

[StickyChannel92]

Instead of restarting Retroarch, it crashes upon loading Apple Town with any NES core, whether it is Mesen, NESTopia, or FCEUmm.

If this happens, where do I put the disksys.rom, if I have a NEStopia core, or FCEUmm core?