Downgrading from MySQL 8 to MySQL 5.7 on Ubuntu 20.x

Yikes! This post is over a year old!
If you think it deserves a rewrite please get in touch or leave a comment.
— Thanks, Ash.

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If you attempt to run a mysqldump on a Ubuntu 20 installation, you may well see the below error:

ERROR 2026 (HY000): SSL connection error: error:1425F102:SSL routines:ssl_choose_client_version:unsupported protocol

Rather than risking downgrading the level of supported SSL routines for MySQL you could instead remove version 8 of the mysql-client package and re-install version 5.7.

Add the new package repository

First, add a new apt repository to the server.

curl -OL https://dev.mysql.com/get/mysql-apt-config_0.8.16-1_all.deb 
sudo dpkg -i mysql-apt-config_0.8.16-1_all.deb

If you see a prompt that states that MySQL is not supported on this system and for you to select from a list. You can navigate your list using arrow keys. Select bionic and then on the next screen it will ask you “Which MySQL product do you wish to configure?”.

Go to “MySQL Server & Cluster” and press ENTER. Then select none from the option list.

Go to “MySQL Tools & Connectors” and press ENTER. Select disabled.

Go to “MySQL Preview Packages” and press ENTER. Select disabled

Finally, go to Ok and press ENTER.

Now you need to make a tweak to the file the script just created. Edit the file and replace it’s contents

sudo nano /etc/apt/sources.list.d/mysql.list

New contents:

### THIS FILE IS AUTOMATICALLY CONFIGURED ### 
# You may comment out entries below, but any other modifications may be lost. 
# Use command 'dpkg-reconfigure mysql-apt-config' as root for modifications. 
deb http://repo.mysql.com/apt/ubuntu/ bionic mysql-apt-config 
deb http://repo.mysql.com/apt/ubuntu/ bionic mysql-5.7 
#deb http://repo.mysql.com/apt/ubuntu/ bionic mysql-tools 
#deb http://repo.mysql.com/apt/ubuntu/ focal mysql-tools-preview 
deb-src http://repo.mysql.com/apt/ubuntu/ bionic mysql-5.7

Save and Exit (CTRL+X, then Y), Then run sudo apt update to update the package cache.

Remove conflicting packages

Next you’ll need to remove the existing packages.

sudo apt-get remove mysql-client mysql-common mysql-community-client mysql-community-server mysql-server

If you get an error:

E: Unable to locate package mysql-community-client 
E: Unable to locate package mysql-community-server

You should re-run the command but remove the mysql-community-client mysql-community-server from the command.

Now you need to check what versions are available to install.

sudo apt-cache policy mysql-client 
mysql-client: 
  Installed: (none) 
 Candidate: 8.0.27-0ubuntu0.20.04.1 
  Version table: 
      8.0.27-0ubuntu0.20.04.1 500 
         500 http://mirror.rackspace.com/ubuntu focal-updates/main amd64 Packages
         500 http://mirror.rackspace.com/ubuntu focal-security/main amd64 Packages
     8.0.19-0ubuntu5 500 
          500 http://mirror.rackspace.com/ubuntu focal/main amd64 Packages 
     5.7.36-1ubuntu18.04 500
         500 http://repo.mysql.com/apt/ubuntu bionic/mysql-5.7 amd64 Packages

Note the version number that starts with 5.7.X in your terminal output and copy the full version to your clipboard. (above example: 5.7.36-1ubuntu18.04)

Install MySQL Client version 5.7

Now re-install mysql-client but specify the version you just copied where i have included $VERSION_NUMBER below.

sudo apt install -f mysql-client=$VERSION_NUMBER -y

You should now have version 5.7 of MySQL installed. You can confirm this by running:

mysql --version 
mysql Ver 14.14 Distrib 5.7.36, for Linux (x86_64) using EditLine wrapper

Your mysqldump should now run fine!