If you have installed MySQL through binaries, you have to remove the symlink to the old version (refer to the Uninstalling MySQL 8 section) and do a fresh installation (refer to the Installing MySQL on Linux using Generic Binaries section).
Once you have downgraded MySQL, you have to restore the backup and run the mysql_upgrade utility:
- Start MySQL (refer to the Starting or Stopping MySQL 8 section). You need to reset the password again.
- Restore the backup (this may take a long time, depending up on the size of backup). Refer to Chapter 8, Restoring Data, for a quick restoration method called myloader:
shell> mysql -u root -p < mysql80.sql
- Run mysql_upgrade:
shell> mysql_upgrade -u root -p
- Restart the MySQL server ...