Yes upgrade from 14.04 to 16.04 isnt problem sometimes …

sudo apt-get update && upgrade ...

sudo apt-get dist-upgrade

sudo do-release-upgrade 

Checking for a new Ubuntu release …

Downloaded milion packages for new version ubuntu… maybe 1200 and more ..

next process was “dpkg: error processsing package … (–configure)” wtf ?

Problem was in mixed package between 14.04 version and 16.04 version!

Ok reboot to recovery ubuntu and repair packages with apt-get and “relocation error … ” wtf…

apt-get: relocation error: /usr/lib/x86_64-linux-gnu/libapt-pkg.so.5.0: symbol _ZNKSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEE7compareERKS4_, version GLIBCXX_3.4.21 not defined in file libstdc++.so.6 with link time reference

solutions: 
sudo dpkg -i libstdc++6_5.3.1-14ubuntu2.1_amd64.deb

ok next bugs … next problem is half packages from 14.04 and next half 16.04 ubuntu …

ok apt-get failed system says :

sudo dpkg --configure -a

This command removed old packages from 14.04

and next problem is “broken snapd and freezing” What The Fuck ? maybe https://bugs.launchpad.net/ubuntu/+source/snapd/+bug/1673247

sudo apt-get remove -f snapd

and next

sudo dpkg --configure -a

uf dpkg reinstaling packages but … waiting 1.2.3.5.minutes.. braille freezed https://askubuntu.com/questions/731671/botched-upgrade-dpkg-hangs-on-started-braille-device-support

[  OK  ] Started Braille Device Support.

oh my God …

sudo apt-get remove -f brltty

ok reinstalling with dpkg and apt-get and now reboot to “new version ” , login to system and again freezed ….