Fatal error: PHP notice in file /www/htdocs/v080184/wbb3/wcf/lib/system/security/SecurityHandler.class.php (338): Array to string conversion

Information:

error message: PHP notice in file /www/htdocs/v080184/wbb3/wcf/lib/system/security/SecurityHandler.class.php (338): Array to string conversion
error code: 0
file: /www/htdocs/v080184/wbb3/wcf/lib/system/WCF.class.php (255)
php version: 5.5.38-nmm2
wcf version: 1.0.11 pl 1 (Horizon)
date: Sat, 22 Sep 2018 15:19:12 +0000
request: /wbb3/wbb/index.php?page=Board&boardID=6&s=be5f583221441cd0f0130605e2fdba0c09cc5561
referer:

Stacktrace:

#0 /www/htdocs/v080184/wbb3/wcf/lib/system/security/SecurityHandler.class.php(338): WCF::handleError(8, 'Array to string...', '/www/htdocs/v08...', 338, Array)
#1 /www/htdocs/v080184/wbb3/wcf/lib/system/security/SecurityHandler.class.php(274): SecurityHandler->generateJournal('flood')
#2 /www/htdocs/v080184/wbb3/wcf/lib/system/security/SecurityHandler.class.php(252): SecurityHandler->attackJournal('flood')
#3 /www/htdocs/v080184/wbb3/wcf/lib/system/security/plugins/blacklist/blacklist.class.php(53): SecurityHandler->accessDenied('flood', Array)
#4 /www/htdocs/v080184/wbb3/wcf/lib/system/security/plugins/blacklist/blacklist.class.php(21): Blacklist->handleList()
#5 /www/htdocs/v080184/wbb3/wcf/lib/system/security/SecurityHandler.class.php(188): Blacklist->execute(Object(SecurityHandler), 'blacklist')
#6 /www/htdocs/v080184/wbb3/wcf/lib/system/security/SecurityHandler.class.php(52): SecurityHandler->fireActions()
#7 /www/htdocs/v080184/wbb3/wcf/lib/system/event/listener/SecurityListener.class.php(34): SecurityHandler->systemCore()
#8 /www/htdocs/v080184/wbb3/wcf/lib/system/event/EventHandler.class.php(117): SecurityListener->execute(Object(BoardPage), 'BoardPage', 'readParameters')
#9 /www/htdocs/v080184/wbb3/wcf/lib/system/event/EventHandler.class.php(142): EventHandler::executeInheritedActions(Object(BoardPage), 'readParameters', 'BoardPage', 'readParameters@...')
#10 /www/htdocs/v080184/wbb3/wcf/lib/page/AbstractPage.class.php(44): EventHandler::fireAction(Object(BoardPage), 'readParameters')
#11 /www/htdocs/v080184/wbb3/wcf/lib/page/MultipleLinkPage.class.php(54): AbstractPage->readParameters()
#12 /www/htdocs/v080184/wbb3/wcf/lib/page/SortablePage.class.php(47): MultipleLinkPage->readParameters()
#13 /www/htdocs/v080184/wbb3/wbb/lib/page/BoardPage.class.php(45): SortablePage->readParameters()
#14 /www/htdocs/v080184/wbb3/wcf/lib/page/AbstractPage.class.php(35): BoardPage->readParameters()
#15 /www/htdocs/v080184/wbb3/wcf/lib/util/RequestHandler.class.php(63): AbstractPage->__construct()
#16 /www/htdocs/v080184/wbb3/wcf/lib/util/RequestHandler.class.php(91): RequestHandler->__construct('Board', Array, 'page')
#17 /www/htdocs/v080184/wbb3/wbb/index.php(8): RequestHandler::handle(Array)
#18 {main}