Broken mysql-server pkg

sudo aptitude -f install mysql-server
The following NEW packages will be installed:
  mysql-server-5.7{a}
The following partially installed packages will be configured:
  mysql-server
0 packages upgraded, 1 newly installed, 0 to remove and 1 not upgraded.
Need to get 0 B/2,466 kB of archives. After unpacking 48.3 MB will be used.
Do you want to continue? [Y/n/?] y
Preconfiguring packages ...
(Reading database ... 320280 files and directories currently installed.)
Preparing to unpack .../mysql-server-5.7_5.7.17-0ubuntu0.16.04.2_amd64.deb ...
Aborting downgrade from (at least) 10.0 to 5.7.
If are sure you want to downgrade to 5.7, remove the file
/var/lib/mysql/debian-*.flag and try installing again.
dpkg: error processing archive /var/cache/apt/archives/mysql-server-5.7_5.7.17-0ubuntu0.16.04.2_amd64.deb (--unpack):
 subprocess new pre-installation script returned error exit status 1
Errors were encountered while processing:
 /var/cache/apt/archives/mysql-server-5.7_5.7.17-0ubuntu0.16.04.2_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
Failed to perform requested operation on package.  Trying to recover:
dpkg: dependency problems prevent configuration of mysql-server:
 mysql-server depends on mysql-server-5.7; however:
  Package mysql-server-5.7 is not installed.

dpkg: error processing package mysql-server (--configure):
 dependency problems - leaving unconfigured
Errors were encountered while processing:
 mysql-server