It looks like there may be an issue with the hard disk or partition located at /dev/sda:
Apr 21 17:50:22 ubuntu-mate kernel: [ 6635.058545] isofs_fill_super: bread failed, dev=sda1, iso_blknum=16, block=32 Apr 21 17:50:22 ubuntu-mate ubiquity: mount: Apr 21 17:50:22 ubuntu-mate ubiquity: wrong fs type, bad option, bad superblock on /dev/sda1, Apr 21 17:50:22 ubuntu-mate ubiquity: missing codepage or helper program, or other error Apr 21 17:50:22 ubuntu-mate ubiquity: Apr 21 17:50:22 ubuntu-mate ubiquity: Apr 21 17:50:22 ubuntu-mate ubiquity: In some cases useful info is found in syslog - try Apr 21 17:50:22 ubuntu-mate ubiquity: dmesg | tail or so. Apr 21 17:50:22 ubuntu-mate ubiquity: mount: Apr 21 17:50:22 ubuntu-mate ubiquity: wrong fs type, bad option, bad superblock on /dev/sda3, Apr 21 17:50:22 ubuntu-mate ubiquity: missing codepage or helper program, or other error Apr 21 17:50:22 ubuntu-mate ubiquity: Apr 21 17:50:22 ubuntu-mate ubiquity: Apr 21 17:50:22 ubuntu-mate ubiquity: In some cases useful info is found in syslog - try Apr 21 17:50:22 ubuntu-mate ubiquity: dmesg | tail or so. Apr 21 17:50:22 ubuntu-mate kernel: [ 6635.297833] EXT4-fs (sda4): mounted filesystem with ordered data mode. Opts: (null) Apr 21 17:50:23 ubuntu-mate kernel: [ 6635.645646] isofs_fill_super: bread failed, dev=sda1, iso_blknum=16, block=32
It looks like there may be an issue with the hard disk or partition located at /dev/sda:
Apr 21 17:50:22 ubuntu-mate kernel: [ 6635.058545] isofs_fill_super: bread failed, dev=sda1, iso_blknum=16, block=32
Apr 21 17:50:22 ubuntu-mate ubiquity: mount:
Apr 21 17:50:22 ubuntu-mate ubiquity: wrong fs type, bad option, bad superblock on /dev/sda1,
Apr 21 17:50:22 ubuntu-mate ubiquity: missing codepage or helper program, or other error
Apr 21 17:50:22 ubuntu-mate ubiquity:
Apr 21 17:50:22 ubuntu-mate ubiquity:
Apr 21 17:50:22 ubuntu-mate ubiquity: In some cases useful info is found in syslog - try
Apr 21 17:50:22 ubuntu-mate ubiquity: dmesg | tail or so.
Apr 21 17:50:22 ubuntu-mate ubiquity: mount:
Apr 21 17:50:22 ubuntu-mate ubiquity: wrong fs type, bad option, bad superblock on /dev/sda3,
Apr 21 17:50:22 ubuntu-mate ubiquity: missing codepage or helper program, or other error
Apr 21 17:50:22 ubuntu-mate ubiquity:
Apr 21 17:50:22 ubuntu-mate ubiquity:
Apr 21 17:50:22 ubuntu-mate ubiquity: In some cases useful info is found in syslog - try
Apr 21 17:50:22 ubuntu-mate ubiquity: dmesg | tail or so.
Apr 21 17:50:22 ubuntu-mate kernel: [ 6635.297833] EXT4-fs (sda4): mounted filesystem with ordered data mode. Opts: (null)
Apr 21 17:50:23 ubuntu-mate kernel: [ 6635.645646] isofs_fill_super: bread failed, dev=sda1, iso_blknum=16, block=32