Hey guys,
I came across this article while troubleshooting the same error going from 5.2.3 to 5.4.4. For me, my issue was resolved by first upgrading to 5.4.1 - see Will Stroll's article on upgrade paths. http://www.willstrohl.com/Blog/EntryId/102/Suggested-DotNetNuke-Site-Upgrade-Path-s
The upgrade ran fine, except I did get the following error. However, the installation/portals seemed to work fine
Executing Script: 05.04.00.SqlDataProvider Error! (see 05.04.00.log for more information)
To resolve this new issue, I ran the following script from Timo (http://www.dotnetnuke.com/Community/Forums/tabid/795/forumid/107/threadid/365005/scope/posts/Default.aspx) which found 2 "ghost" portals - ones I created then deleted later. I then ran Sebastian's script to remove those rows.
After all that. I ran the 5.4.4 upgrade, which installed fine without any errors. Unfortunately, it took me a few hours to dig around and find these solutions. Hopefully this might help some save a few hours, if it works for them.