Ah I thought we were all through with this one
You replaced your config file when you upgraded so the variables that where needed for the 4.8.6 where not there. The upgrade instructions state not to ever replace the config file. Thus the queries that needed to be entered from settings that were in an old style config where never entered.
Manually use phpmyadmin and enter the queries by hand.
INSERT INTO `settings` VALUES (166, 'BotBuster Integration', 'botbuster', 'Set to yes if you have BotBuster on your system (this includes the necessary tag)', 'no', 22, 1);
INSERT INTO `settings` VALUES (167, 'Enable ZLIB page compression', 'compression', 'Set to on if you want to enable Zlib page compression (and it is supported)', 'yes', 23, 1);
INSERT INTO `settings` VALUES (168, 'Date format', 'ppdateformat', 'Keywords: dow, month, mm, dd, yyyy', 'month dd , yyyy', 24, 1);
INSERT INTO `settings` VALUES (169, 'GMT Offset', 'gmtoffset', 'If you are running
VB and want the server to display the time as an offset of GMT (for example, to the timezone where your server is located), enter t', '-1', 25, 1);
INSERT INTO `settings` VALUES (170, 'Enable IP Cache Timeout', 'ipcache', 'This variable is used to track IP addresses and userids for voting and viewing purposes. This is set in HOURS. 0 disables this setting', '0', 26, 1);
INSERT INTO `settings` VALUES (171, 'PhotoPost Cookie Path', 'cookie_path', 'This should be set to match the path/domain for your cookies. Setting to / enables entire site.', '/', 1, 12);
INSERT INTO `settings` VALUES (172, 'Forum Cookie Prefix', 'cookieprefix', 'Some Default values vB3: bb, phpBB2: phpbb2mysql, Threads: w3t_', 'reeftalk', 2, 12);
INSERT INTO `settings` VALUES (173, 'PhotoPost Cookie Domain', 'domain_path', '.yourdomain.com; sets the cookie to be usable across the domain', '.reeftalk.com', 3, 12);
INSERT INTO `settings` VALUES (174, 'Debug Setting', 'debug', 'How do you want PhotoPost to handle errors?', '0', 27, 1);
INSERT INTO `settings` VALUES (175, 'Enable On-The-Fly Watermarks', 'onthefly', 'Requires GD2 and you must edit the file watermark.php', 'no', 29, 5);
INSERT INTO `settings` VALUES (176, 'Imaging Integration (IM or GD)', 'usegd', 'Select ImageMagick or GD1/GD2 for image processing', '0', 28, 1);
INSERT INTO `settings` VALUES (177, 'Directory for backups?', 'backupdir', 'The full path to the directory to store backups', '/var/www/html/backups', 29, 1);
INSERT INTO `settings` VALUES (178, 'Path to mysqldump', 'mysqldumppath', 'The full path to your mysqldump executable', '/usr/bin/mysqldump', 30, 1);
INSERT INTO `settings` VALUES (179, 'Path to jpegtran (if used)', 'jpegtran', 'If you would like to clean any JPG image uploaded before being processed; enter the path to your jpegtran executable.', '/usr/X11R6/bin/jpegtran', 18, 1);
INSERT INTO `settings` VALUES (180, 'Path to jhead (if used)', 'jhead_command', 'This only needs to be set if you are extracting EXIF information from images. Full server path.', '/usr/X11R6/bin/jhead', 19, 1);
INSERT INTO `settings` VALUES (181, 'Gallery Open?', 'ppboards', 'Yes for Open, No for Closed', 'open', 20, 1);
INSERT INTO `settings` VALUES (182, 'Message displayed when closed', 'closedmsg', '', 'The boards are temporarily down for maintainence.', 21, 1);