[ubuntu] Unable to boot after upgrade in Ubuntu 15.10

Hey. Thank you for your answer!

Today I found out that Ubuntu 15.10 is no longer supported. I will upgrade to 16.04 as soon as I have fixed the boot problem (when I manage to do it).

You're right indeed. I can see in term.log several lines with GRUB, efi and Boot.

Is there a standard procedure to deal with this problem?

I am helpless.

Here the history.log:

Start-Date: 2016-08-11 00:31:53
Commandline: aptdaemon role='role-commit-packages' sender=':1.107'
Install: linux-image-extra-4.2.0-42-generic:amd64 (4.2.0-42.49, automatic), linux-image-4.2.0-42-generic:amd64 (4.2.0-42.49, automatic), mokutil:amd64 (0.3.0-0ubuntu3~15.10.1, automatic), linux-headers-4.2.0-42:amd64 (4.2.0-42.49, automatic), linux-headers-4.2.0-42-generic:amd64 (4.2.0-42.49, automatic), linux-signed-image-4.2.0-42-generic:amd64 (4.2.0-42.49, automatic)
Upgrade: shim-signed:amd64 (1.11+0.8-0ubuntu2, 1.18~15.10.1+0.8-0ubuntu2), linux-headers-generic:amd64 (4.2.0.41.44, 4.2.0.42.45), libarchive13:amd64 (3.1.2-11ubuntu0.15.10.1, 3.1.2-11ubuntu0.15.10.2), dh-python:amd64 (2.20150826ubuntu1, 2.20150826ubuntu1.1), flashplugin-installer:amd64 (11.2.202.626ubuntu0.15.10.1, 11.2.202.632ubuntu0.15.10.1), thermald:amd64 (1.4.3-5ubuntu2, 1.4.3-5ubuntu3), libpurple0:amd64 (2.10.11-0ubuntu4.1, 2.10.11-0ubuntu4.2), linux-signed-generic:amd64 (4.2.0.41.44, 4.2.0.42.45), libpurple-bin:amd64 (2.10.11-0ubuntu4.1, 2.10.11-0ubuntu4.2), linux-signed-image-generic:amd64 (4.2.0.41.44, 4.2.0.42.45), linux-libc-dev:amd64 (4.2.0-41.48, 4.2.0-42.49), linux-image-generic:amd64 (4.2.0.41.44, 4.2.0.42.45), linux-generic:amd64 (4.2.0.41.44, 4.2.0.42.45)
End-Date: 2016-08-11 00:35:35