I had a Trusty 14.04 LTS system and used update-manager -d to trigger the release upgrade to Xenial. Everything went fine, but when I rebooted into the kernel 4.4.0-22-generic I was greeted with a stacktrace and an error about not being able to execute /sbin/init on the initrd.
I booted into the old kernel and extracted and compared the initrd's and everything important was the same. I then booted with boot_delay=250 and after a long wait was able to see "request_module: runaway loop modprobe binfmt-464c" messages indicating wrong binary format. Then I looked at the kernel config and noticed that CONFIG_X86_64 was not defined on the upgrade kernel; afterwards, I saw that linux-image-generic:i386 and friends were installed.
After replacing linux-image-generic:i386 and friends with the amd64 variants, all was fine.
Please ensure that if linux-image-generic is installed or replaced, its arch matches the arch of /sbin/init or systemd perhaps?
ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubuntu-release-upgrader-core 1:16.04.14
ProcVersionSignature: Ubuntu 4.4.0-22.40-generic 4.4.8
Uname: Linux 4.4.0-22-generic x86_64
NonfreeKernelModules: openafs
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CrashDB: ubuntu
Date: Sun May 29 21:22:01 2016
JournalErrors:
Error: command ['journalctl', '-b', '--priority=warning', '--lines=1000'] failed with exit code 1: Hint: You are currently not seeing messages from other users and the system.
Users in the 'systemd-journal' group can see all messages. Pass -q to
turn off this notice.
No journal files were opened due to insufficient permissions.
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to xenial on 2016-05-30 (0 days ago)
VarLogDistupgradeAptclonesystemstate.tar.gz:
Error: command ['pkexec', 'cat', '/var/log/dist-upgrade/apt-clone_system_state.tar.gz'] failed with exit code 127: polkit-agent-helper-1: error response to PolicyKit daemon: GDBus.Error:org.freedesktop.PolicyKit1.Error.Failed: No session for cookie
Error executing command as another user: Not authorized
This incident has been reported.
VarLogDistupgradeApttermlog: Error: [Errno 13] Permission denied: '/var/log/dist-upgrade/apt-term.log'
VarLogDistupgradeTermlog:
Or just check uname -m and don't install a different arch kernel during the upgrade. :-)