I had to change the MySQL password to the old format, then I was able to connect. But, I'm getting a new error now:
Script: /Library/Tenon/WebServer/WebSites/www.realtree.com/forums/ubbt.inc.php
Line#: 1608
SQL Error: Table 'ubb-realtree.w3t_Users' doesn't exist
SQL Error #: 1146
Query: SELECT U_Username,U_Password,U_SessionId, U_StyleSheet, U_Status, U_Privates, U_FrontPage, U_Number, U_Banned,U_LastOn,U_OC_Userid FROM w3t_Users WHERE U_Number = ''
Aren't table names case sensitive? If so, ubb-realtree.w3t_Users should be ubb-realtree.w3t_users
And, a clean install of 6.5.5 is working. This is weird.
