ubuntu@ip-172-31-45-14X:~$ sudo apt-get clean && apt-get autoclean
E: Could not open lock file /var/cache/apt/archives/lock - open (13: Permission denied)
E: Unable to lock the download directory
ubuntu@ip-172-31-45-14X:~$ sudo apt-get -f install
Reading package lists... Done
Building dependency tree
Reading state information... Done
Correcting dependencies... Done
The following packages were automatically installed and are no longer required:
  libdbd-mysql-perl libdbi-perl libmysqlclient20 libterm-readkey-perl mariadb-common
Use 'sudo apt autoremove' to remove them.
The following additional packages will be installed:
  mysql-server-5.7
Suggested packages:
  mailx tinyca
The following NEW packages will be installed:
  mysql-server-5.7
0 upgraded, 1 newly installed, 0 to remove and 23 not upgraded.
1 not fully installed or removed.
Need to get 2,597 kB of archives.
After this operation, 48.3 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://eu-central-1.ec2.archive.ubuntu.com/ubuntu xenial-updates/main amd64 mysql-server-5.7 amd64 5.7.23-0ubuntu0.16.04.1 [2,597 kB]
Fetched 2,597 kB in 0s (28.5 MB/s)
Preconfiguring packages ...
(Reading database ... 93623 files and directories currently installed.)
Preparing to unpack .../mysql-server-5.7_5.7.23-0ubuntu0.16.04.1_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_5.7.23-0ubuntu0.16.04.1_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_5.7.23-0ubuntu0.16.04.1_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
ubuntu@ip-172-31-45-14X:~$ sudo dpkg --configure -a
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
ubuntu@ip-172-31-45-14X:~$ sudo apt-get -f install
Reading package lists... Done
Building dependency tree
Reading state information... Done
Correcting dependencies... Done
The following packages were automatically installed and are no longer required:
  libdbd-mysql-perl libdbi-perl libmysqlclient20 libterm-readkey-perl mariadb-common
Use 'sudo apt autoremove' to remove them.
The following additional packages will be installed:
  mysql-server-5.7
Suggested packages:
  mailx tinyca
The following NEW packages will be installed:
  mysql-server-5.7
0 upgraded, 1 newly installed, 0 to remove and 23 not upgraded.
1 not fully installed or removed.
Need to get 0 B/2,597 kB of archives.
After this operation, 48.3 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Preconfiguring packages ...
(Reading database ... 93623 files and directories currently installed.)
Preparing to unpack .../mysql-server-5.7_5.7.23-0ubuntu0.16.04.1_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_5.7.23-0ubuntu0.16.04.1_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_5.7.23-0ubuntu0.16.04.1_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
ubuntu@ip-172-31-45-14X:~$