This is my first time posting, I hope I am in the right area.  I also searched but couldn't find anything relating to my problem.After updating to 2.3 I keep getting 2 to 4 of these warnings messages across the top of the category pages on the front end of my site. Warning: is_array() [function.is-array]:
Only one argument expected in /home/website/public_html/plugins/system/nonumberelements/helpers/assignments.php
on line 447.There weren't any error messages during the update and everything seems to be working correctly except for these warning messages.  I am on a hosted server with Joomla 1.5.15, PHP 5.2.12 and MySQL 5.0.90.  Any help would be appreciated.

Try going to Components - K2, Paramaters - and save them.
this may fix the problem if its the same as others have had

Thank you William for your suggestion. Unfortunately, that didn't work. I've just started building the website so I am going to uninstall/reinstall K2 and see if that fixes things.