Hello,

It took me some time to realize why I was not able to install Debian
with software RAID1 system. The reason is that when I was running the
Guided partitioning on the whole software RAID disk, partman-auto would
create an EFI partition there, and thus even if I had created an EFI
partition outside the RAID, grub would try to use the partition inside
the RAID. If partman-auto wasn't creating an EFI partition inside the
RAID, I wouldn't have had any issue.

Samuel