Kernel panic, target filesystem doesn't have request /sbin/init afeter upgrade from 14.04 to 16.04

[Damien]

1/ ubuntu 14.04.5 LTS
   release 14.04
2/ package version:
ubuntu@ubuntu:/$ sudo apt-cache policy pkgname
N: Unable to locate package pkgname
ubuntu@ubuntu:/$ 1473366353536 addons.update-checker WARN Update manifest for <email address hidden> did not contain an updates property
1473366353735 addons.update-checker WARN Update manifest for <email address hidden> did not contain an updates property
1473366354375 addons.update-checker WARN Update manifest for {972ce4c6-7e08-4474-a285-3208198ce6fd} did not contain an updates property
1473366354561 addons.update-checker WARN Update manifest for <email address hidden> did not contain an updates property
1473366356240 addons.xpi ERROR Attempted to load bootstrap scope from missing directory /home/ubuntu<email address hidden>
1473366356240 addons.xpi WARN Add-on <email address hidden> is missing bootstrap method shutdown
1473366356253 addons.manager WARN Exception calling callback: [Exception... "Component returned failure code: 0x80520006 (NS_ERROR_FILE_TARGET_DOES_NOT_EXIST) [nsIFile.isDirectory]" nsresult: "0x80520006 (NS_ERROR_FILE_TARGET_DOES_NOT_EXIST)" location: "JS frame :: resource://gre/modules/addons/XPIProvider.jsm :: getURIForResourceInFile :: line 1517" data: no] Stack trace: getURIForResourceInFile()@resource://gre/modules/addons/XPIProvider.jsm:1517 < this.XPIProvider.callBootstrapMethod()@resource://gre/modules/addons/XPIProvider.jsm:4786 < this.XPIProvider.uninstallAddon()@resource://gre/modules/addons/XPIProvider.jsm:5064 < AddonWrapper.prototype.uninstall()@resource://gre/modules/addons/XPIProvider.jsm:7300 < uninstallHotfix/<()@resource://gre/modules/addons/XPIProvider.jsm -> jar:file:///home/ubuntu<email address hidden>!/bootstrap.js:93 < safeCall()@resource://gre/modules/AddonManager.jsm:179 < makeSafe/<()@resource://gre/modules/AddonManager.jsm:195 < Handler.prototype.process()@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:937 < this.PromiseWalker.walkerLoop()@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:816 < this.PromiseWalker.scheduleWalkerLoop/<()@resource://gre/modules/Promise.jsm -> resource://gre/modules/Promise-backend.js:750

3/ I let software&update application making the upgrade to 16.04 LTS as recommended.
   it crashed on reboot.

4/ No way to get recovery from linux-image-4.4.0-36-generic (4.4.0-36.55~14.04.1) ...
   nor from previous linux/image-3.3.39

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubuntu-release-upgrader-core 1:0.220.8
ProcVersionSignature: Ubuntu 4.4.0-31.50~14.04.1-generic 4.4.13
Uname: Linux 4.4.0-31-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.21
Architecture: amd64
CasperVersion: 1.340.2
CrashDB: ubuntu
CurrentDesktop: Unity
Date: Thu Sep 8 20:17:40 2016
LiveMediaBuild: Ubuntu 14.04.5 LTS "Trusty Tahr" - Release amd64 (20160803)
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to trusty on 2016-09-08 (0 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.