Configuration file '/etc/mysql/debian-start'
 ==> Deleted (by you or by a script) since installation.
 ==> Package distributor has shipped an updated version.
   What would you like to do about it ?  Your options are:
    Y or I  : install the package maintainer's version
    N or O  : keep your currently-installed version
      D     : show the differences between the versions
      Z     : start a shell to examine the situation
 The default action is to keep your current version.
*** debian-start (Y/I/N/O/D/Z) [default=N] ? N
update-alternatives: warning: alternative /etc/mysql/mariadb.cnf (part of link group my.cnf) doesn't exist; removing from list of alternatives
update-alternatives: warning: alternative /etc/mysql/my.cnf.fallback (part of link group my.cnf) doesn't exist; removing from list of alternatives
update-alternatives: warning: /etc/alternatives/my.cnf is dangling; it will be updated with best choice
update-alternatives: using /etc/mysql/mysql.cnf to provide /etc/mysql/my.cnf (my.cnf) in auto mode
Renaming removed key_buffer and myisam-recover options (if present)
ERROR: Unable to start MySQL server:
mysqld: Can't read dir of '/etc/mysql/conf.d/' (Errcode: 2 - No such file or directory)
mysqld: [ERROR] Fatal error in defaults handling. Program aborted!
Please take a look at https://wiki.debian.org/Teams/MySQL/FAQ for tips on fixing common upgrade issues.
Once the problem is resolved, run apt-get --fix-broken install to retry.
dpkg: error processing package mysql-server-5.7 (--configure):
 subprocess installed post-installation script returned error exit status 1
dpkg: dependency problems prevent configuration of mysql-server:
 mysql-server depends on mysql-server-5.7; however:
  Package mysql-server-5.7 is not configured yet.

dpkg: error processing package mysql-server (--configure):
 dependency problems - leaving unconfigured
Processing triggers for systemd (229-4ubuntu21.4) ...
No apport report written because the error message indicates its a followup error from a previous failure.
                                                                                                          Processing triggers for ureadahead (0.100.0-19) ...
Errors were encountered while processing:
 mysql-server-5.7
 mysql-server
E: Sub-process /usr/bin/dpkg returned an error code (1)
ubuntu@ip-172-31-45-140:~$