Selecting “MBR for BIOS or UEFI” when your target PC expects pure UEFI (or vice versa) doesn’t always cause immediate failure—but sometimes it confuses Rufus’s patching routine. The tool attempts to write both legacy and UEFI bootloaders, runs out of space or conflicts, and aborts.
To understand why Rufus can’t “patch” or “setup” boot files, you first need to understand what Rufus actually does when it creates a bootable drive. rufus unable to patch/setup files for boot