You may have a 64-bit only installation of mingw32-w64 then. Try this: pacman -U /var/cache/pacman/pkg/mingw-w64-x86_64-gcc-10.1.0-3-any.pkg.tar.zst /var/cache/pacman/pkg/mingw-w64-x86_64-gcc-libs-10.1.0-3-any.pkg.tar.zst and assuming you had gcc 10.1.0-3 installed, that should work to downgrade you...