Re: Problem with MySQL-Upgrade V8.0.37 -> V8.4.5

[Nick R]

Thanks for the detailed explanation, Oliver. You did most things right, but the issue is that MySQL is still starting from the old service or data folder.

Root Cause
Even though you installed MySQL 8.4.5 in a new folder and created a new service (MySQL845), it’s still reading the old data or config file (my.ini) from version 8.0.37.
That’s why SELECT VERSION() still shows 8.0.37.

How to Fix

Step 1. Check which service is running
Run in Command Prompt (Admin):

sc query type= service | find "MySQL"


You should see MySQL80 and MySQL845.
Stop both:

net stop mysql80
net stop mysql845


Then start only the new one:

net start mysql845


Check again with SELECT VERSION();

If it still shows 8.0.37, the new service is using the old config.

Step 2. Check the service configuration
Run:

sc qc mysql845


Look for BINARY_PATH_NAME.
It should point to something like:

d:\MySQL8.4.5\Program\bin\mysqld.exe --defaults-file="d:\MySQL8.4.5\Data\my.ini"


If it points to the old MySQL folder, reinstall the service:

sc delete mysql845
cd D:\MySQL8.4.5\Program\bin
mysqld --install MySQL845 --defaults-file="D:\MySQL8.4.5\Data\my.ini"


Step 3. Fix the paths in my.ini
Make sure these lines are correct:

basedir=D:/MySQL8.4.5/Program
datadir=D:/MySQL8.4.5/Data


Do not use Daten\Data unless that folder exists.

Step 4. Initialize the data folder if empty

If Data is empty, run:

mysqld --defaults-file="D:\MySQL8.4.5\Data\my.ini" --initialize-insecure


Then start the service again.

Step 5. Automatic upgrade

MySQL 8.4 upgrades automatically on startup if it finds an older data directory.
To confirm the upgrade:

SHOW VARIABLES LIKE 'version%';


It should show version 8.4.5.

Please let me know if you are still receiving the same error. I will reproduce the error from my end and share a solution to fix it.

Nick R
Cloud Team Lead
AccuWeb.Cloud