MySQL In-place upgrade creates a new instance instead of upgrading the existing one

All we need is an easy explanation of the problem, so here it is.

I am doing an in-place upgrade from mysql 5.7.26 to 5.7.33. I have done from 5.6 to 5.7 for serveral hosts and did not face this issue.

Followed below steps

  1. Took a VM snapshot and mysqldump as well.
  2. systemctl stop mysqld
  3. removed mysql 5.7.26 rpms
  4. yum install mysql-community-common-5.7.33-1.el7.x86_64
  5. yum install mysql-community-libs-5.7.33-1.el7.x86_64
  6. yum install mysql-community-libs-compat-5.7.33-1.el7.x86_64
  7. yum install mysql-community-client-5.7.33-1.el7.x86_64
  8. yum install mysql-community-server-5.7.33-1.el7.x86_64
  9. systemctl start mysqld

After installed 5.7.33 rpms, when i tried to run mysql_upgrade ,I realized my password is’nt working and then when i checked i saw a new empty /etc/my.cnf file and new instance under /var/lib/mysql. I could still see my actual data directory intact.

Why is this issue because i never faced it before. If i replace the empty my.cnf with my actual my.cnf and restart the mysqld service, will it be a solution to my problem.

Thanks

How to solve :

I know you bored from this bug, So we are here to help you! Take a deep breath and look at the explanation of your problem. We have many solutions to this problem, But we recommend you to use the first method because it is tested & true method that will 100% work for you.

Method 1

Dont know why this issue. Removing 5.7.26 rpms actually renames the /etc/my.cnf to /etc/my.cnf.rpmsave. Installing 5.7.33 rpms creates a plain new /etc/my.cnf . So when i start mysqld, it creates a new datadir in /var/lib/mysql. After removing old rpms, i renamed /etc/my.cnf.rpmsave to /etc/my.cnf and started mysqld and ran mysql_upgrade. All good now. I upgraded to mysql 5.7.33 in many servers, did not face the issue anywhere. only difference i see is my.cnf is owned by mysql in working servers while it is owned by root in current scenario

Note: Use and implement method 1 because this method fully tested our system.
Thank you 🙂

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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