hi, i got this error too - the upgrade database script did not complete properly - the problem was solved for me by a fresh publish of my existing database and rerunning the upgrade script over it
I also received this error. I always dread upgrading any web site software since it often doesn't go smooth.
To get the error I had v 1.50 installed.
I removed all the files.
I copied in all the v1.60 files.
I navigated to the install.aspx page
I checked "upgrade" and next.
I entered the db server info and clicked next.
This is when I got the error.
I then manually ran the upgrade script and it completed successfully. I did not need to restore my old database. i then renamed the install directory, copied my theme in and updated the styles.css file and verified that the site worked.
Oh, also manually updated the connectionstrings.config (or whatever it is called) file... I may have done this before the db info page since the file is readonly.