Hi guys,
So I had this issue when trying to install from 1.5 to 1.7 it didn't matter if I had 1.5 then 1.6 to 1.7 same issue..
So what I end up doing, is get a new fresh backup of my site...
save to my computer then in my Mysql server , created a new DB specifying the COLLATION of the database -> utf8_general_ci
you get an empty DATA BASE, then just import your backup, go to website url/ow_updates and update your site..
In my case was successful ..
Hope it helps someone.