Hello I have made an installation mistake while trying to install the complete prequisities for Postfix sudo apt-get install postfix postfix-mysql dovecot-core dovecot-imapd dovecot-pop3d dovecot-lmtpd dovecot-mysql mysql-server dovecot-sieve dovecot-managesievedbut the server already had mySQL 8 installed... So from now on whenver i install something i also get this : Setting up mysql-server-5.7 (5.7.30-0ubuntu0.16.04.1) ... Renaming removed key_buffer and myisam-recover options (if present) Job for mysql.service failed because the control process exited with error code. See "systemctl status mysql.service" and "journalctl -xe" for details. invoke-rc.d: initscript mysql, action "start" failed. ● mysql.service - MySQL Community Server Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled) Active: activating (auto-restart) (Result: exit-code) since Mon 2020-07-06 06:19:07 UTC; 5ms ago Process: 9757 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=1/FAILURE) Jul 06 06:19:07 ip-172-26-11-59 systemd: mysql.service: Control process e...1 Jul 06 06:19:07 ip-172-26-11-59 systemd: Failed to start MySQL Community .... Jul 06 06:19:07 ip-172-26-11-59 systemd: mysql.service: Unit entered fail.... Jul 06 06:19:07 ip-172-26-11-59 systemd: mysql.service: Failed with resul.... Hint: Some lines were ellipsized, use -l to show in full. 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 Setting up rar (2:5.3.b2-1) ... No apport report written because the error message indicates its a followup error from a previous failure. Errors were encountered while processing: mysql-server-5.7 mysql-server E: Sub-process /usr/bin/dpkg returned an error code (1) Any clue on how to clear this ?