CComment docs

JoomlaComment3 and 4.0

If you are upgrading from JoomlaComment 3+,4+ to CompojoomComment 4.1 you should do the following.

  1. Make a Backup

  2. Make a Backup

  3. Did I say make a Backup???

Now after you have made sure that you have made a Backup you can log into your backend. Go to Components-> !joomlacomment -> content settings . In the settings find the parameter uninstall complete mode and make sure that it is set to no. If it isn’t, set it to no and click save. If this setting is set to yes and you uninstall joomlacomment you are going to lose your comments, because the database tables will be dropped when you uninstall it. (We don’t want this, do we???)

Now you need to update to version 4.2.1 first and after that you can update to version 5.