I don't know because ISPConfig 2.2.5 asked to me the name of the old database. I renamed the old (under 2.2.3) in the new and it seems there are no problems.
I remember that yesterday ISPConfig 2.2.5 installer asked for the name and for the certificates (already loaded) and immediately stopped with some errors (such as in the first installation).
I repeated the installation and the second time I not configured certificates (simply press 'enter' to go on) and the installer not asked me more nothing (?).
Now it seems all work correctly, but I'm not sure. Eventually can I uninstall ISPConfig (totally) and reinstall it?!? If Mysql Db is preserved I suppose there will be not probems to do that.
Thank you very much.