Hello Florian,
> For me the Guix System installer crashes reproducibly after manual > partitioning, even when not formatting the partition. The ESP and > root partition have not been deleted (no matter if I tell the > installer to format them or not). This applies to EFI installation on > my 2010 Macbook but not in QEMU. Perhaps the reason is the partition > I’m trying to format previously was LUKS-encrypted. Could you share your hard drive layout (size and partitions) and the content of `dmesg' and `/var/log/messages' ? Thanks for your help, Mathieu