Fatal error: PHP error in file /var/www/clients/client1/web1/web/portal/wcf/lib/util/DLDBUtil.class.php (234): Non-static method DLDBUtil::getAllowedKat() should not be called statically

Information:

error message: PHP error in file /var/www/clients/client1/web1/web/portal/wcf/lib/util/DLDBUtil.class.php (234): Non-static method DLDBUtil::getAllowedKat() should not be called statically
error code: 0
file: /var/www/clients/client1/web1/web/portal/wcf/lib/system/WCF.class.php (255)
php version: 5.6.30-0+deb8u1
wcf version: 1.0.11 pl 4 (Horizon)
date: Sun, 17 Dec 2017 09:46:30 +0000
request: /portal/index.php?page=DownloadDB&s=363664a9d924ed4732d3e21584638126f6f2bec4
referer:

Stacktrace:

#0 /var/www/clients/client1/web1/web/portal/wcf/lib/util/DLDBUtil.class.php(234): WCF::handleError(2048, 'Non-static meth...', '/var/www/client...', 234, Array)
#1 /var/www/clients/client1/web1/web/portal/wcf/lib/util/DLDBUtil.class.php(234): DLDBUtil::getAllowedKat()
#2 /var/www/clients/client1/web1/web/portal/wcf/lib/page/DownloadDBPage.class.php(100): DLDBUtil::countDatas()
#3 /var/www/clients/client1/web1/web/portal/wcf/lib/page/DownloadDBPage.class.php(39): DownloadDBPage->makeStats()
#4 /var/www/clients/client1/web1/web/portal/wcf/lib/page/AbstractPage.class.php(74): DownloadDBPage->readData()
#5 /var/www/clients/client1/web1/web/portal/wcf/lib/page/DownloadDBPage.class.php(92): AbstractPage->show()
#6 /var/www/clients/client1/web1/web/portal/wcf/lib/page/AbstractPage.class.php(36): DownloadDBPage->show()
#7 /var/www/clients/client1/web1/web/portal/wcf/lib/util/RequestHandler.class.php(63): AbstractPage->__construct()
#8 /var/www/clients/client1/web1/web/portal/wcf/lib/util/RequestHandler.class.php(91): RequestHandler->__construct('DownloadDB', Array, 'page')
#9 /var/www/clients/client1/web1/web/portal/index.php(8): RequestHandler::handle(Array)
#10 {main}