Bootloader not installed on USB

[Nero]

I'm installing Qubes on Macbook Air.
I partitioned (EFI, Macos journalled) my SSD but Qubes installer do not see any partitions on SSD but see my 32GB USB stick.
1. Why I can not install on SSD?

Ok, trying to install on USB goes ok until message like "boot loader can not be written" at the end of installation.
Trying to boot with this installations get me to "grub>" only.

Can I fix my USB somehow? Maybe I can write bootloader manually?

Thanks!

[Jean-Philippe Ouellet]

In case you haven't seen it already, have you read through the MacBook
troubleshooting page [1], particularly the sections "4. Fix GRUB
configuration", and "5. Fix bootloader"?

[1]: https://www.qubes-os.org/doc/macbook-troubleshooting/

Regards,
Jean-Philippe

[Nero]

Thank you!
But I already quit Qubes installation program and "chrooot /mnt/sysimage" do nothing. And I can not find files like "/boot/efi/EFI/qubes/xen.cfg" to edit on my installation USB. Actually when mounted under OSX it contains only one file: "/Volumes/Linux HFS+ ESP/EFI/qubes/xen-4.6.1.efi"

Do I have to run installation again or there is a way to fix bootloader on my USB without running installation?
I'm pretty new to UNIX systems so exact command would be helpfull, thank you!

[Nero]

I installed Qubes again on USB disk, opened terminbal and tried to follow instructions for fixing -
https://www.qubes-os.org/doc/macbook-troubleshooting/

But it seems that some files are missing - see screenshot.
chroot /mnt/sysimage says "no such file or directory"
/boot/efi/EFI/qubes/xen.cfg was empty or missing - I made it in "vi"
configfile - command not found