Hi,
I'm beginning honestly to think that someone is messing with the old version of BB 
We did nothing (no updates, no plugin installation, no nothing) and this happened, what is happening with BB 3.1.x ?
Code
Fatal error: Invalid SQL: UPDATE wcf1_acp_session SET userData = '' WHERE userID IN (1)
You get more information about the problem in our knowledge base: http://www.woltlab.com/help/?code=1054
Information:
error message: Invalid SQL: UPDATE wcf1_acp_session SET userData = '' WHERE userID IN (1)error code: 1054sql type: MySQLDatabasesql error: Unknown column 'userData' in 'field list'sql error number: 1054sql version:file: /var/www/clients/client0/web1/web/wcf/lib/system/database/MySQLDatabase.class.php (118)php version: 5.4.45-0+deb7u2wcf version: 1.1.10 pl 2 (Tempest)date: Wed, 20 Apr 2016 07:48:05 +0000request: /referer: http://reapercrew.ro/
Stacktrace:
#0 /var/www/clients/client0/web1/web/wcf/lib/system/session/Session.class.php(718): MySQLDatabase->sendQuery('UPDATE\twcf1_acp...')#1 /var/www/clients/client0/web1/web/wcf/lib/data/user/UserEditor.class.php(331): Session::resetSessions('1')#2 /var/www/clients/client0/web1/web/wcf/lib/data/user/UserEditor.class.php(324): UserEditor->resetSession()#3 /var/www/clients/client0/web1/web/wcf/lib/data/user/UserEditor.class.php(241): UserEditor->updateUser('', '', '', Array)#4 /var/www/clients/client0/web1/web/wcf/lib/data/user/UserEditor.class.php(276): UserEditor->update('', '', '', NULL, Array)#5 /var/www/clients/client0/web1/web/wcf/lib/system/event/listener/UserOnlineTimerListener.class.php(43): UserEditor->updateOptions(Array)#6 /var/www/clients/client0/web1/web/wcf/lib/system/event/EventHandler.class.php(131): UserOnlineTimerListener->execute(Object(IndexPage), 'IndexPage', 'show')#7 /var/www/clients/client0/web1/web/wcf/lib/system/event/EventHandler.class.php(156): EventHandler::executeInheritedActions(Object(IndexPage), 'show', 'IndexPage', 'show@IndexPage')#8 /var/www/clients/client0/web1/web/wcf/lib/page/AbstractPage.class.php(96): EventHandler::fireAction(Object(IndexPage), 'show')#9 /var/www/clients/client0/web1/web/wcf/lib/page/AbstractPage.class.php(46): AbstractPage->show()#10 /var/www/clients/client0/web1/web/wcf/lib/util/RequestHandler.class.php(64): AbstractPage->__construct()#11 /var/www/clients/client0/web1/web/wcf/lib/util/RequestHandler.class.php(92): RequestHandler->__construct('Index', Array, 'page')#12 /var/www/clients/client0/web1/web/index.php(8): RequestHandler::handle(Array)#13 {main}Even if this above is fixed, once @ 2 days i must empty the cache tables from mysql.
(this error also came to life this year, about 2 months ago, you can check my post here also, the solution presented does not work either)