Fetched 8,535 kB in 29s (293 kB/s)
Preconfiguring packages ...
Selecting previously unselected package mysql-common.
(Reading database ... 279056 files and directories currently installed.)
Preparing to unpack .../mysql-common_5.5.57-0ubuntu0.14.04.1_all.deb ...
Unpacking mysql-common (5.5.57-0ubuntu0.14.04.1) ...
Selecting previously unselected package libmysqlclient18:i386.
Preparing to unpack .../libmysqlclient18_5.5.57-0ubuntu0.14.04.1_i386.deb ...
Unpacking libmysqlclient18:i386 (5.5.57-0ubuntu0.14.04.1) ...
Selecting previously unselected package libdbd-mysql-perl.
Preparing to unpack .../libdbd-mysql-perl_4.025-1ubuntu0.1_i386.deb ...
Unpacking libdbd-mysql-perl (4.025-1ubuntu0.1) ...
Selecting previously unselected package mysql-client-core-5.5.
Preparing to unpack .../mysql-client-core-5.5_5.5.57-0ubuntu0.14.04.1_i386.deb ...
Unpacking mysql-client-core-5.5 (5.5.57-0ubuntu0.14.04.1) ...
Selecting previously unselected package mysql-client-5.5.
Preparing to unpack .../mysql-client-5.5_5.5.57-0ubuntu0.14.04.1_i386.deb ...
Unpacking mysql-client-5.5 (5.5.57-0ubuntu0.14.04.1) ...
Selecting previously unselected package mysql-server-core-5.5.
Preparing to unpack .../mysql-server-core-5.5_5.5.57-0ubuntu0.14.04.1_i386.deb ...
Unpacking mysql-server-core-5.5 (5.5.57-0ubuntu0.14.04.1) ...
Processing triggers for man-db (2.6.7.1-1ubuntu1) ...
Setting up mysql-common (5.5.57-0ubuntu0.14.04.1) ...
Selecting previously unselected package mysql-server-5.5.
(Reading database ... 279247 files and directories currently installed.)
Preparing to unpack .../mysql-server-5.5_5.5.57-0ubuntu0.14.04.1_i386.deb ...
Aborting downgrade from (at least) 5.6 to 5.5.
If are sure you want to downgrade to 5.5, remove the file
/var/lib/mysql/debian-*.flag and try installing again.
dpkg: error processing archive /var/cache/apt/archives/mysql-server-5.5_5.5.57-0ubuntu0.14.04.1_i386.deb (--unpack):
 subprocess new pre-installation script returned error exit status 1
Selecting previously unselected package mysql-server.
Preparing to unpack .../mysql-server_5.5.57-0ubuntu0.14.04.1_all.deb ...
Unpacking mysql-server (5.5.57-0ubuntu0.14.04.1) ...
Errors were encountered while processing:
 /var/cache/apt/archives/mysql-server-5.5_5.5.57-0ubuntu0.14.04.1_i386.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)