GRUB2 - Booting ISO from USB-Drive gives ERROR - KDE neon, ArchLinux, Windows 10 - MuliBoot

I am trying to set up a multiboot ISO USB-Drive and I get error messages when I start the ISO file.

As I see it, the loopback device is executed properly, otherwise no iso would start. However, the correct path cannot be found.
I do not understand why.
Maybe the loop device needs some more options or GUBB2 needs some modules.

1. The "KDE neon GNU/Linux (.iso)" boots without any problems.

2. The "Arch Linux (.iso)" gives the following error message:

> Booting a command list
> error: no such module.
> Press any key to continue…

After pressing the Enter key the following happens

> Waiting for boot device ...
> Waiting 30 seconds for device /dev/disk/by-label/ARCH_202211 ...
> ERROR: ’/dev/disk/by-label/ARCH_202211’ device didn't show up after 30 seconds...
> Falling back to interactive prompt.

3. The "Windows 10 (.iso)" does not find the file.

> Booting a command list
> error:no such module.
> error: file '/efi/boot/bootx64.efi' not found
> Press any key to continue…

If I unpack the iso and copy it directly on the partition, windows boots without problems with this command (grub.cfg):

search.fs_uuid 2222-UUID-2222 root hd0,gpt1 set prefix=($root)'/grub' configfile $prefix/grub.cfg menuentry 'Windows 10' { chainloader (${root})/efi/boot/bootx64.efi }

My configuration

**USB-Drive:** fdisk -l /dev/sdb && lsblk -pf /dev/sdb Disk /dev/sdb: 7.48 GiB, 8021606400 bytes, 15667200 sectors Disk model: USB storage device Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: gpt Disk identifier: 0000-UUID-0000 Device Start End Sectors Size Type /dev/sdb1 2048 206847 204800 100M EFI System /dev/sdb2 206848 15667166 15460319 7.4G Microsoft basic data NAME FSTYPE LABEL UUID FSAVAIL FSUSE% MOUNTPOINT /dev/sdb ├─/dev/sdb1 vfat EFI 1111-UUID-1111 └─/dev/sdb2 ntfs BOOT 2222-UUID-2222 I installed the USB-Drive as described in the GNU GRUB manual grub-install --efi-directory=/mnt/EFI --boot-directory=/mnt/BOOT --removable **grub.cfg:** search.fs_uuid 2222-UUID-2222 root hd0,gpt2 set prefix=($root)'/grub' configfile $prefix/grub.cfg menuentry "KDE neon GNU/Linux ISO" { rmmod tpm set isofile="/KDEneon.iso" loopback loop (${root})/$isofile linux (loop)/casper/vmlinuz boot=casper apparmor=0 iso-scan/filename=$isofile noprompt noeject lang=en locale=de_DE.UTF-8 initrd (loop)/casper/initrd } menuentry "Arch Linux ISO" { rmmod tpm set isofile="/ArchLinux.iso" loopback loop (${root})/$isofile search --no-floppy --set=root --label ARCH_202211 linux (loop)/arch/boot/x86_64/vmlinuz-linux archisobasedir=arch archisolabel=ARCH_202211 iso-scan/filename=$isofile noprompt noeject lang=en locale=de_DE.UTF-8 initrd (loop)/arch/boot/intel-ucode.img (loop)/arch/boot/amd-ucode.img (${root})/arch/boot/x86_64/initramfs-linux.img } menuentry 'Windows 10 ISO' { rmmod tpm set isofile="/Windows10.iso" loopback loop (${root})/$isofile chainloader (loop)/efi/boot/bootx64.efi iso-scan/filename=$isofile noprompt noeject } menuentry 'Windows 10 Extracted' { chainloader (${root})/efi/boot/bootx64.efi } #menuentry 'memtest' { # #} menuentry 'UEFI Settings' --class uefi { fwsetup } menuentry "Restart" --class reboot { reboot } menuentry "Power Off" --class halt { halt } **--- EDIT ---** I installed the ArchLinux.iso with DD on the USB drive and this is what the drive looks like. sudo dd if=/home/anonymus/Downloads/ArchLinux.iso of=/dev/sdb status=progress > fdisk -l /dev/sdb && lsblk -pf /dev/sdb && cat Disk /dev/sdb: 7.48 GiB, 8021606400 bytes, 15667200 sectors Disk model: USB storage device Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0000-UUID-0000 Device Boot Start End Sectors Size Id Type /dev/sdb1 * 64 1570815 1570752 767M 0 Empty /dev/sdb2 1570816 1601535 30720 15M ef EFI (FAT-12/16/32) NAME FSTYPE LABEL UUID FSAVAIL FSUSE% MOUNTPOINT /dev/sdb iso9660 ARCH_202211 2022-11-01-13-53-46-00 ├─/dev/sdb1 iso9660 ARCH_202211 2022-11-01-13-53-46-00 0 100% /mnt/ARCH_202211 └─/dev/sdb2 vfat ARCHISO_EFI 55DC-6BC5 > Arch Linux grub.cfg # Load partition table and file system modules insmod part_gpt insmod part_msdos insmod fat insmod iso9660 # Use graphics-mode output insmod all_video insmod font if loadfont "${prefix}/fonts/unicode.pf2" ; then insmod gfxterm set gfxmode="auto" terminal_input console terminal_output gfxterm fi # Enable serial console if serial --unit=0 --speed=115200; then terminal_input --append serial terminal_output --append serial fi # Set default menu entry default=archlinux timeout=15 timeout_style=menu # GRUB init tune for accessibility play 600 988 1 1319 4 # Menu entries menuentry "Arch Linux install medium (x86_64, UEFI)" --class arch --class gnu-linux --class gnu --class os --id 'archlinux' { set gfxpayload=keep search --no-floppy --set=root --label ARCH_202211 linux /arch/boot/x86_64/vmlinuz-linux archisobasedir=arch archisolabel=ARCH_202211 initrd /arch/boot/intel-ucode.img /arch/boot/amd-ucode.img /arch/boot/x86_64/initramfs-linux.img } menuentry "Arch Linux install medium with speakup screen reader (x86_64, UEFI)" --hotkey s --class arch --class gnu-linux --class gnu --class os --id 'archlinux-accessibility' { set gfxpayload=keep search --no-floppy --set=root --label ARCH_202211 linux /arch/boot/x86_64/vmlinuz-linux archisobasedir=arch archisolabel=ARCH_202211 accessibility=on initrd /arch/boot/intel-ucode.img /arch/boot/amd-ucode.img /arch/boot/x86_64/initramfs-linux.img } if [ "${grub_platform}" == "efi" ]; then if [ "${grub_cpu}" == "x86_64" ]; then menuentry "UEFI Shell" { insmod chain search --no-floppy --set=root --label ARCH_202211 chainloader /shellx64.efi } elif [ "${grub_cpu}" == "i386" ]; then menuentry "UEFI Shell" { insmod chain search --no-floppy --set=root --label ARCH_202211 chainloader /shellia32.efi } fi menuentry 'UEFI Firmware Settings' --id 'uefi-firmware' { fwsetup } fi menuentry "System shutdown" --class shutdown --class poweroff { echo "System shutting down..." halt } menuentry "System restart" --class reboot --class restart { echo "System rebooting..." reboot }