Ok, your steps were:
1) Downloaded the patch from
http://www.jforum.net/confluence/display/configuration/MySQL+3.23
2) Unpacked it into your jforum's root dir.
3) Admin Panel -> Groups -> Permissions -> Save
4) Got the error.
that's correct? or there are somethign different?
For me, looks like you didn't do all necessary steps in order to get the patch correctly applied. Your stack trace points to
however, this is the old class. The new one is "MySQL323GroupSecurityDAO". I guess you forgot this step:
....open the file WEB-INF/config/database/mysql/mysql.properties and change the key dao.driver to net.jforum.drivers.mysql.MySQL323DataAccessDriver
take a better read there.
Rafael
[originally posted on jforum.net by Rafael Steil]