It may be a coincidence but yesterday I installed some libguestfs-tools. Now I see errors when booting, which also appear in /var/log/messages:
kernel: [ 9.506798] sr 3:0:0:0: [sr0] tag#12 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE cmd_age=2s kernel: [ 9.507009] sr 3:0:0:0: [sr0] tag#12 Sense Key : Not Ready [current] kernel: [ 9.507146] sr 3:0:0:0: [sr0] tag#12 Add. Sense: Medium not present - tray closed kernel: [ 9.507304] sr 3:0:0:0: [sr0] tag#12 CDB: Read(10) 28 00 00 07 ff fc 00 00 02 00 kernel: [ 9.507731] sr 3:0:0:0: [sr0] tag#31 unaligned transfer kernel: [ 9.513520] sr 3:0:0:0: [sr0] tag#13 unaligned transfer kernel: [ 9.529995] sr 3:0:0:0: [sr0] tag#14 unaligned transfer kernel: [ 9.602797] sr 3:0:0:0: [sr0] tag#3 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE cmd_age=0s kernel: [ 9.608514] sr 3:0:0:0: [sr0] tag#3 Sense Key : Not Ready [current] kernel: [ 9.614297] sr 3:0:0:0: [sr0] tag#3 Add. Sense: Medium not present - tray closed kernel: [ 9.620170] sr 3:0:0:0: [sr0] tag#3 CDB: Read(10) 28 00 00 00 00 00 00 00 02 00 kernel: [ 9.631993] sr 3:0:0:0: [sr0] tag#4 unaligned transfer kernel: [ 9.650464] sr 3:0:0:0: [sr0] tag#5 unaligned transfer I removed the toos, and also disabled udiskd or udisk2d: systemctl stop udisks2.service systemctl disable udisks2.service But the errors are still occuring. How can I stop them? Installing the tools did some strange things like regenerating the grub menu.