xorriso cannot find file in ISO image

I'm trying to create a bootable ISO using xorriso, but I get this error: xorriso : FAILURE : Cannot find in ISO image: -boot_image ... bin_path='' It's [not just me](https://www.google.com/search?q= "Cannot+find+in+ISO+image") who gas gotten this error. The message doesn't make sense either because I never used -boot_image and xorriso should not be looking for isolinux.bin in any ISO. The path to isolinux.bin that I gave is the root directory of an already-unpacked ISO that I'm modifying.