Uninstalling MySQL Server on Ubuntu: A Comprehensive Guide

Encountering issues while trying to uninstall Mysql Server on your Ubuntu system can be frustrating. Often, a simple apt remove command isn’t enough, and you might run into errors like “dpkg error processing package mysql-server”. This guide provides a detailed walkthrough to completely uninstall MySQL server, ensuring a clean removal and resolving common dependency problems.

Understanding the “dpkg Error Processing Package MySQL Server”

The error message you’re seeing typically indicates that MySQL server is in a partially installed or configured state. This often happens when dependencies aren’t correctly managed during the removal process. The core issue is that remnants of the mysql-server-5.7 package (or a similar version-specific package) are still lingering on your system, causing conflicts when you try to remove the main mysql-server package.

Here’s a typical error message you might encounter:

dpkg: error processing package mysql-server (--configure):
 dependency problems - leaving unconfigured
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)

This error essentially tells you that mysql-server-5.7, a dependency of mysql-server, is already installed but not fully configured. To resolve this, you need to explicitly purge both the main package and its version-specific dependency to eliminate any leftover configurations and data.

The most effective solution is to use the purge command in apt. Unlike remove, purge aims to remove not only the package binaries but also its configuration files, offering a more thorough cleanup.

sudo apt purge mysql-server mysql-server-5.7

Step-by-Step Guide to Uninstall MySQL Server

To ensure a complete and clean uninstallation of your MySQL server, follow these steps:

1. Check the Status of the MySQL Service

Before attempting to uninstall, it’s crucial to check if the MySQL service is currently running. An active service might interfere with the uninstallation process. We can use systemctl, the systemd control utility, to check the service status.

systemctl status mysql.service

If MySQL is running, you’ll see output similar to this:

● mysql.service - MySQL Community Server
     Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
     Active: active (running) since Tue 2023-10-24 10:00:00 UTC; 1h ago
       Docs: man:mysqld(8)
             man:mysql_config_editor(1)
             http://dev.mysql.com/doc/refman/en/using-systemd.html
   Main PID: 1234 (mysqld)
     Status: "Server is operational"
      Tasks: 38 (limit: 4628)
     Memory: 456.7M
        CPU: 1min 34.567s
     CGroup: /system.slice/mysql.service
             └─1234 /usr/sbin/mysqld

If the service is inactive or not found, you can skip to step 3.

2. Stop the MySQL Service

If the MySQL service is active, you need to stop it before proceeding with the uninstallation. Use the systemctl stop command:

sudo systemctl stop mysql

This command will halt the MySQL server process. You can verify that the service has stopped by running the status command again: systemctl status mysql.service. It should now indicate that the service is inactive.

In rare cases, stop might not work. If so, you can try using kill with systemctl:

sudo systemctl kill mysql

However, stop is generally the preferred and cleaner method.

3. Purge MySQL Server Packages

Now, it’s time to uninstall the MySQL server packages. As mentioned earlier, purge is recommended for a thorough removal. This command will remove the MySQL server, client, common files, and specific version core components.

Warning: The following commands can potentially delete your MySQL databases. Ensure you have backups of any critical data before proceeding.

To back up your MySQL data, you can use the following command:

tar -zcvf ~/mysql_backup.tar.gz /etc/mysql /var/lib/mysql

This command creates a compressed archive (mysql_backup.tar.gz) in your home directory containing the /etc/mysql configuration directory and the /var/lib/mysql data directory.

After backing up (or if you don’t need to back up your data), proceed with purging the packages:

sudo apt purge mysql-server mysql-client mysql-common mysql-server-core-* mysql-client-core-*

The mysql-server-core-* and mysql-client-core-* patterns ensure that version-specific core packages are also removed, regardless of the specific version installed (like mysql-server-core-5.7).

4. Remove Remaining Configuration Files and Data Directories

Even after purging, some configuration files and data directories might still remain. To completely clean up, you can manually remove these directories.

Double Warning: This step will permanently delete your MySQL data files if they still exist. Ensure you have a backup if needed before running these commands.

sudo rm -rf /etc/mysql /var/lib/mysql

This command recursively removes (-r) and forcefully deletes (-f) the /etc/mysql and /var/lib/mysql directories and their contents.

5. Autoremove and Autoclean Unnecessary Dependencies

After purging and removing directories, you can use apt autoremove and apt autoclean to clean up any leftover dependencies and package archives that are no longer needed.

sudo apt autoremove
sudo apt autoclean

autoremove removes packages that were installed as dependencies and are no longer required by any installed packages. autoclean clears out the local repository of retrieved package files that are no longer necessary.

6. Fixing Broken Packages and Missing Dependencies (If Necessary)

In some situations, especially if you’ve had interrupted installations or removals, you might encounter broken packages or dependency issues even after purging. apt provides options to fix these problems.

First, update your package lists:

sudo apt update

Then, you can try to fix broken packages and missing dependencies using the --fix-broken and --fix-missing options with apt install:

sudo apt install mysql-server mysql-client --fix-broken --fix-missing

Even though we are trying to uninstall, running install with these flags can help apt resolve inconsistencies in its package database. After running this, you might need to repeat the purge process from step 3.

7. Manual Installation as a Last Resort

If none of the above steps work, and you are still facing issues, a more advanced approach is to manually download, compile, and install MySQL from source. This is generally not necessary for most users and is considered a last resort. Instructions for manual installation are beyond the scope of this guide but are available in the official MySQL documentation. For typical uninstall issues on Ubuntu, the previous steps should be sufficient.

Conclusion

Completely uninstalling MySQL server on Ubuntu requires more than just a simple remove command. By using purge, stopping the service, and removing leftover directories, you can ensure a clean removal and resolve common “dpkg error” issues. Remember to back up your data if necessary before proceeding with the uninstallation process. This comprehensive guide should help you successfully remove MySQL server from your Ubuntu system.