Fatal error: PHP notice in file /var/www/vhosts/web776.michelle.webhoster.ag/httpdocs/wbblite2/wcf/lib/system/auth/UserAuthDefault.class.php (56): Use of undefined constant COOKIE_PREFIX - assumed 'COOKIE_PREFIX'

Information:

error message: PHP notice in file /var/www/vhosts/web776.michelle.webhoster.ag/httpdocs/wbblite2/wcf/lib/system/auth/UserAuthDefault.class.php (56): Use of undefined constant COOKIE_PREFIX - assumed 'COOKIE_PREFIX'
error code: 0
file: /var/www/vhosts/web776.michelle.webhoster.ag/httpdocs/wbblite2/wcf/lib/system/WCF.class.php (255)
php version: 5.4.16
wcf version: 1.0.11 pl 4 (Horizon)
date: Wed, 16 Jan 2019 22:37:25 +0000
request: /index.php?form=Mail&userID=1868&s=88908b31c34a84cc6e80e1b4830d2f4a4cad911b
referer:

Stacktrace:

#0 /var/www/vhosts/web776.michelle.webhoster.ag/httpdocs/wbblite2/wcf/lib/system/auth/UserAuthDefault.class.php(56): WCF::handleError(8, 'Use of undefine...', '/var/www/vhosts...', 56, Array)
#1 /var/www/vhosts/web776.michelle.webhoster.ag/httpdocs/wbblite2/wcf/lib/system/session/CookieSessionFactory.class.php(34): UserAuthDefault->loginAutomatically(true, 'WBBUserSession')
#2 /var/www/vhosts/web776.michelle.webhoster.ag/httpdocs/wbblite2/wcf/lib/system/session/SessionFactory.class.php(71): CookieSessionFactory->create()
#3 /var/www/vhosts/web776.michelle.webhoster.ag/httpdocs/wbblite2/lib/system/WBBCore.class.php(170): SessionFactory->get()
#4 /var/www/vhosts/web776.michelle.webhoster.ag/httpdocs/wbblite2/wcf/lib/system/WCF.class.php(91): WBBCore->initSession()
#5 /var/www/vhosts/web776.michelle.webhoster.ag/httpdocs/wbblite2/global.php(18): WCF->__construct()
#6 /var/www/vhosts/web776.michelle.webhoster.ag/httpdocs/wbblite2/index.php(7): require_once('/var/www/vhosts...')
#7 {main}