I'm actually doing an internship in a company, so they asked me to update their Ubuntu before starting my job. The problem is that when I do the "do-release-upgrade", I've got an error message and system recovery to the original. Then I checked in the main.log and I have those lines:
2019-07-03 09:34:48,879 INFO Using config files '['./DistUpgrade.cfg.trusty']'
2019-07-03 09:34:48,879 INFO uname information: 'Linux AWARE 3.16.0-30-generic #40~14.04.1-Ubuntu SMP Thu Jan 15 17:43:14 UTC 2015 x86_64'
2019-07-03 09:34:49,431 INFO apt version: '1.0.1ubuntu2.23'
2019-07-03 09:34:49,431 INFO python version: '3.4.3 (default, Nov 12 2018, 22:25:49)
[GCC 4.8.4]'
2019-07-03 09:34:49,436 INFO release-upgrader version '16.04.26' started
2019-07-03 09:34:49,445 INFO locale: 'fr_FR' 'UTF-8'
2019-07-03 09:34:49,459 DEBUG screen returned: 'No Sockets found in /var/run/screen/S-root. 2019-07-03 09:34:49,460 INFO re-exec inside screen: '['screen', '-e', '\\0\\0', '-L', '-c', 'screenrc', '-S', 'ubuntu-release-upgrade-screen-window', '/tmp/ubuntu-release-upgrader-p0eywysq/xenial', '--mode=server', '--frontend=DistUpgradeViewText']'
