Quote Originally Posted by DrByte View Post
Prior to 1.5.7 that constant was defined in the whos online language file. In 1.5.7 it chooses a default if it's not defined.
I can't speak to the plugin you're using: maybe you're using a version of it that's not ready for 1.5.7?
You didn't quote the log details which explain the name of the file where the warning is occurring, so it's increasingly difficult to give any sort of useful assistance.

Thank you for mentioning that. I looked and compared the whos_online.php file to the 1.5.7 file and they were different so I copied the newest one from the 1.5.7 zen version and I believe that fixed it. I am not getting any error logs now. I am so sorry for the bother. I should have checked that to begin with. I do appreciate your help.