Chat funktioniert nicht mehr seit Update auf WBB4.1.1

Fatal error: objectID and tmpHash cannot be empty at the same time
Information:
id: 839415f0900cb694ca7d1e09e91fa7145c61201c
error message: objectID and tmpHash cannot be empty at the same time
error code: 0
file: /www/htdocs/w0081ab3/kaffeewelt/forum/wbb4/wcf/lib/system/attachment/AttachmentHandler.class.php (66)
php version: 5.5.22-nmm1
wcf version: 2.1.1 (Typhoon)
date: Sat, 14 Mar 2015 10:12:05 +0000
request: /chat/index.php/Chat/1-Kaffee-Welt-net-Chat/
referer: http://www.kaffee-welt.net/
Stacktrace:
#0 /www/htdocs/w0081ab3/kaffeewelt/forum/wbb4/chat/lib/page/ChatPage.class.php(137): wcf\system\attachment\AttachmentHandler->__construct('be.bastelstu.ch...', 0, '', 0)
#1 /www/htdocs/w0081ab3/kaffeewelt/forum/wbb4/wcf/lib/page/AbstractPage.class.php(265): chat\page\ChatPage->readData()
#2 /www/htdocs/w0081ab3/kaffeewelt/forum/wbb4/chat/lib/page/ChatPage.class.php(212): wcf\page\AbstractPage->show()
#3 /www/htdocs/w0081ab3/kaffeewelt/forum/wbb4/wcf/lib/page/AbstractPage.class.php(100): chat\page\ChatPage->show()
#4 /www/htdocs/w0081ab3/kaffeewelt/forum/wbb4/wcf/lib/system/request/Request.class.php(58): wcf\page\AbstractPage->__run()
#5 /www/htdocs/w0081ab3/kaffeewelt/forum/wbb4/wcf/lib/system/request/RequestHandler.class.php(139): wcf\system\request\Request->execute()
#6 /www/htdocs/w0081ab3/kaffeewelt/forum/wbb4/chat/index.php(10): wcf\system\request\RequestHandler->handle('chat')
#7 {main}