I have a droplet with Ubuntu 14.04.5 x64. When I run the command:

apt-get update

I get this error (I will copy paste the last few rows of the terminal):

My-server:~# apt-get update
.........
Get:80 http://mirrors.digitalocean.com trusty/universe i386 Packages [5866 kB]
Get:81 http://mirrors.digitalocean.com trusty/multiverse i386 Packages [134 kB]
Get:82 http://mirrors.digitalocean.com trusty/main Translation-en [762 kB]
Get:83 http://mirrors.digitalocean.com trusty/multiverse Translation-en [102 kB]
Get:84 http://mirrors.digitalocean.com trusty/restricted Translation-en [3457 B]
Get:85 http://mirrors.digitalocean.com trusty/universe Translation-en [4089 kB]
Ign http://repo.mysql.com trusty/mysql-5.7 Translation-en
Ign http://repo.mysql.com trusty/mysql-apt-config Translation-en
Ign http://repo.mysql.com trusty/mysql-tools Translation-en
E: Method https has died unexpectedly!
E: Sub-process https received signal 9.
My-server:~#

How to fix the error?