it is mentioned on the wiki that you need to kill mongodb linux default database:
however i prefer to just change the port, here i put my launch file for KB:
<?xml version="1.0"?>
<launch>
<!-- the full path for the domain.pddl -->
<arg name="domain_path" default="$(find pddl_learning)/common/pddl/domain.pddl" />
<!-- select a problem.pddl to be parsed and uploaded as initial state to KB -->
<arg name="problem_path" default="$(find pddl_learning)/common/pddl/problems/water_plant.pddl" />
<!-- the place in which mongoDB will store runtime files -->
<arg name="database_path" default="$(find pddl_learning)/common/mongoDB" />
<!-- the desired ROS namespace -->
<arg name="namespace" default="task_planning" />
<!-- mongoDB related parameters -->
<arg name="mongodb_host" default="localhost" />
<arg name="mongodb_port" default="27019" /> <!-- Do not use ubuntu default mongodb port : 27017-->
<!-- scene database (MongoDB) -->
<node pkg="mongodb_store" type="mongodb_server.py" name="mongodb_server"
output="screen" ns="$(arg namespace)" >
<param name="master" value="false"/>
<param name="host" value="$(arg mongodb_host)" />
<param name="port" value="$(arg mongodb_port)" />
<param name="database_path" value="$(arg database_path)" />
</node>
<!-- scene database messages (MongoDB) -->
<param name="$(arg namespace)/mongodb_host" type="str" value="$(arg mongodb_host)" />
<param name="$(arg namespace)/mongodb_port" type="int" value="$(arg mongodb_port)" />
<node pkg="mongodb_store" type="message_store_node.py" name="message_store_node"
output="screen" ns="$(arg namespace)" />
<!-- rosplan knowledge base node-->
<node pkg="rosplan_knowledge_base" type="knowledgeBase" name="rosplan_knowledge_base"
output="log" required="true" ns="$(arg namespace)" >
<param name="domain_path" value="$(arg domain_path)" />
<param name="problem_path" value="$(arg problem_path)" />
</node>
</launch>