Logs of failure:
Checking for a new Ubuntu release
Get:1 Upgrade tool signature [819 B]
Get:2 Upgrade tool [1,251 kB]
Fetched 1,252 kB in 0s (0 B/s)
authenticate 'bionic.tar.gz' against 'bionic.tar.gz.gpg'
extracting 'bionic.tar.gz'
Reading cache
Checking package manager
Reading package lists... Done
Building dependency tree
Reading state information... Done
Get:14 http://archive.ubuntu.com/ubuntu xenial-backports/universe amd64 DEP-11 Metadata [6,612 B]
Fetched 1,215 kB in 0s (0 B/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
Checking for installed snaps
Calculating snap size requirements
Updating repository information
Third party sources disabled
Some third party entries in your sources.list were disabled. You can
re-enable them after the upgrade with the 'software-properties' tool
or your package manager.
To continue please press [ENTER]
Get:69 http://archive.ubuntu.com/ubuntu bionic-backports/universe DEP-11 64x64 Icons [6,808 B]
Fetched 59.7 MB in 6s (2,909 kB/s)
Checking package manager
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating the changes
Calculating the changes
Restoring original system state
Aborting
Reading package lists... Done
Building dependency tree
Reading state information... Done
There is no issue in apt.log
main.log output
2023-06-23 10:13:05,145 DEBUG Free space on /: 4048220160
2023-06-23 10:13:05,145 DEBUG Dir /usr mounted on /
2023-06-23 10:13:05,145 DEBUG Dir /var mounted on /
2023-06-23 10:13:05,145 DEBUG Dir /boot mounted on /
2023-06-23 10:13:05,146 DEBUG Dir /var/cache/apt/archives mounted on /
2023-06-23 10:13:05,146 DEBUG Dir /tmp mounted on /
2023-06-23 10:13:05,146 DEBUG Free space on /home: 59700662272
2023-06-23 10:13:05,146 DEBUG Dir /tmp mounted on /
2023-06-23 10:13:05,146 DEBUG fs_free contains: '{'/tmp': <DistUpgrade.DistUpgradeCache.MyCache.checkFreeSpace.<locals>.FreeSpace object at 0x7f9378d16780>, '/var': <DistUpgrade.DistUpgradeCache.MyCache.checkFreeSpace.<locals>.FreeSpace object at 0x7f9378d16780>, '/home': <DistUpgrade.DistUpgradeCache.MyCache.checkFreeSpace.<locals>.FreeSpace object at 0x7f9378d168d0>, '/boot': <DistUpgrade.DistUpgradeCache.MyCache.checkFreeSpace.<locals>.FreeSpace object at 0x7f9378d16780>, '/usr': <DistUpgrade.DistUpgradeCache.MyCache.checkFreeSpace.<locals>.FreeSpace object at 0x7f9378d16780>, '/var/cache/apt/archives': <DistUpgrade.DistUpgradeCache.MyCache.checkFreeSpace.<locals>.FreeSpace object at 0x7f9378d16780>, '/': <DistUpgrade.DistUpgradeCache.MyCache.checkFreeSpace.<locals>.FreeSpace object at 0x7f9378d16780>}'
2023-06-23 10:13:06,678 DEBUG dir '/var/cache/apt/archives' needs '0' of '<DistUpgrade.DistUpgradeCache.MyCache.checkFreeSpace.<locals>.FreeSpace object at 0x7f9378d16780>' (4048220160.000000)
2023-06-23 10:13:06,678 DEBUG dir '/usr' needs '0' of '<DistUpgrade.DistUpgradeCache.MyCache.checkFreeSpace.<locals>.FreeSpace object at 0x7f9378d16780>' (4048220160.000000)
2023-06-23 10:13:06,678 DEBUG dir '/usr' needs '52428800' of '<DistUpgrade.DistUpgradeCache.MyCache.checkFreeSpace.<locals>.FreeSpace object at 0x7f9378d16780>' (4048220160.000000)
2023-06-23 10:13:06,678 DEBUG dir '/boot' needs '66868533.9' of '<DistUpgrade.DistUpgradeCache.MyCache.checkFreeSpace.<locals>.FreeSpace object at 0x7f9378d16780>' (3995791360.000000)
2023-06-23 10:13:06,678 DEBUG dir '/tmp' needs '5242880' of '<DistUpgrade.DistUpgradeCache.MyCache.checkFreeSpace.<locals>.FreeSpace object at 0x7f9378d16780>' (3928922826.100000)
2023-06-23 10:13:06,679 DEBUG dir '/' needs '10485760' of '<DistUpgrade.DistUpgradeCache.MyCache.checkFreeSpace.<locals>.FreeSpace object at 0x7f9378d16780>' (3923679946.100000)
2023-06-23 10:13:06,679 DEBUG dir '/tmp' needs '0.0' of '<DistUpgrade.DistUpgradeCache.MyCache.checkFreeSpace.<locals>.FreeSpace object at 0x7f9378d16780>' (3913194186.100000)
2023-06-23 10:13:06,679 DEBUG dir '/usr' needs '0.0' of '<DistUpgrade.DistUpgradeCache.MyCache.checkFreeSpace.<locals>.FreeSpace object at 0x7f9378d16780>' (3913194186.100000)
2023-06-23 10:13:06,679 DEBUG Found writable ESP /dev/nvme0n1p1 /boot/efi vfat rw,relatime,fmask=0077,dmask=0077,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro 0 0
2023-06-23 10:13:06,692 DEBUG found components: {'bionic-updates': {'main', 'restricted', 'universe', 'multiverse'}, 'bionic-security': {'main', 'restricted', 'universe', 'multiverse'}, 'bionic': {'universe', 'restricted', 'main', 'multiverse'}}
2023-06-23 10:13:06,692 DEBUG abort called
2023-06-23 10:13:06,700 DEBUG openCache()
2023-06-23 10:13:09,653 DEBUG /openCache(), new cache size 93393
2023-06-23 10:13:09,653 DEBUG enabling apt cron job
No error message found hence not able to figure the reason of failure? Any suggestions?
