Last weekend I upgraded from 5.2x to 7.01 and it pretty much went fine. When upgrading to 5.5 I received the error ""Error: Duplicate entry '223' for key 1" errors and "Error: Duplicate column name 'lastphoto'" but otherwise all was ok and worked fine.
I did however start to receive some emails with query problems as shown below:
SELECT id,user,userid,cat,storecat,date,title,description,ismature, keywords,bigimage,width,height,filesize,views, medwidth,medheight,medsize,approved,rating,votes, allowprint,numcom,lastposter FROM pp_photos WHERE userid= AND storecat=0 ORDER BY disporder, date DESC
The query returned with an errorcode of:
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'AND storecat=0 ORDER BY disporder,date DESC' at line 1
If you need assistence or feel this is a 'bug'; please report it to our support forums at: Photopost Pro Bug Reports - PhotoPost Community
A quick look at the code indicates that userID was not filled in, but I don't know what query/feature is being run when this happens.