Originally thought my issue was an 3 to 4 upgrade problem but when I back tracked today I discovered my local 3.X clone had the same issue. Running on MAMP, ioncube installed. To verify the environment I have both a vanilla 3.x and 4.x install running on the same server with no issues. Did a reinstall of my production system using the step by step instructions in this thread still end up with access to the ACP and the forum homepage, but when I try any forum I get "requested URL /test_p15d24ph_forum/forum/4-p15-d24-forum/ was not found on this server." I'm stumped at this point. I guess next try is re-download files from my production server and try again. Looking for suggestions.