Hi Alexandre,

Regarding your issue, loo like there is a conflict between EasyDiscuss and your system plugin 'K2 - System Plugin'. Somehow this plugin alter the model include path in EasyDiscuss. To fix this issue, I've modified your K2 system plugin file 'JOOMLA/plugins/system/k2.php' and added below code at line 385:

if (JFactory::getApplication()->isAdmin() && JRequest::getCmd('option', '') == 'com_easydiscuss') {

	return;

}

Now you no longer hit the warning message when saving a category from your EasyDiscuss.

Hope this help and have a nice day!