Apparently generating a proposal for /dev/vda failed and then a proposal for /dev/sda is generated: 2018-11-12 23:05:36 <1> install(3871) [Ruby] y2storage/guided_proposal.rb:139 Failed to make a proposal using root device /dev/vda: Y2Storage::Error 2018-11-12 23:05:36 <1> install(3871) [Ruby] y2storage/guided_proposal.rb:130 Trying to make a proposal with target desired and root /dev/sda But the reason for the failure for /dev/vda is unclear.