Bug #19797 innodb_data_home_dir gets dropped from my.ini when reconfiguring instance

Description:

Using the MYSQL Instance Configuration tool installed as part of the basic MYSQL installation to turn off strict mode when diagnosing an installation problem with a web application, my service failed to restart.  

I rebooted my laptop to see if it was a transient problem and it was not.

By comparing my.ini files with previous backups, I found that the value for innodb_data_home_dir was not in the updated my.ini file.  A diff of the old and new files showed this and the change to the strict mode setting as the only two differences in the files.

As I use a custom location ( entered through the wizard during install ), any default values it may have decided to use would not have worked.  This may be why it has not popped up before on the bug database.

I classified it as serious, as it stops the database from being started ever again until the my.ini file is corrected.  For some people, it could be significant.

How to repeat:
Install Mysql latest version onto a windows machine.  set the database location to be a non-default location and then accept all of the defaults.

Start mysql and verify all is working as expected.

Run the instance configuration tool and reconfigure existing instance.  Go through and turn off strict mode.

The database location is greyed out when you go through the wizard.

database fails to restart after writing out my.ini.

The above should work, although I've not tested it out as I am a little tied up using it.  

Suggested fix:
Fix Instance Configuration Wizard to not drop the setting.

Thank you for a problem report. What exact latest version should be checked? 5.1.9-beta or 5.0.21?

This was identified on a 5.0.21 installation of mysql ( or at least I think it was ).

Please, check if it was 5.0.21. Version is written in the error log upon each startup.

It was version 5.0.21.  Error log extract included below for validation.

Version: '5.0.21-community-nt'  socket: ''  port: 3306  MySQL Community Edition (GPL)

Verified just as described with 5.0.22. It is MySQL Instance Config Wizard bug.

Ok to push

Verified changes to Instance Configuration Wizard correct this issue.  
Tested with 5.0.51 on Windows XP.

Refer to Bug#6627 regarding other possible difficulties in setting Innodb Tablespace paths.

Noted in 5.1.24 changelog.

MySQLInstanceConfig.exe could lose the innodb_data_home_dir setting
when reconfiguring an instance. 

Resetting report to Patch queued waiting for push into 6.0.x.

Noted in 6.0.5 changelog.