i have seeing a lot of apache logs with this entry:
[error] PHP Notice: Undefined index: 5329ca476139eroom_created in chatroom.php on line 146

All the support for chatroom was disabled in the configuration enviroment.

Yes, in ACL in freichat backend.

Do you get these errors on every page load ?

yes , on every page load.

The show_chatroom_plugin variable may be auto disabled when the guests and registered users dont use the chat room feature.
Anyway, i changed manually the arg.php, and the error dissapeared.

When reading the code at chatroom.php-> get_rooms
IMO the line
if ($first == 'false' || $first == 'ajax') {
//get all chatrooms on first req

should be changed to

if ($first == 'true' || $first == 'ajax') {
//get all chatrooms on first req