failed to call update polygone service

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Hello,

I am trying to run the frontier_exploration on ROS Melodic for turtlebot3. I use turtltebot3_slam from turtlebot3 and exploration_server from frontier_exploration.

I just changed the plugin name frontier_exploration::BoundedExploreLayer to polygon_layer::PolygonLayer in frontier_exploration.yaml.

After I run the turtlebot3_frontier_exploration.launch, make the polygon and clicked on a initial point for the exploration, I have the folllowing error :

[ INFO] [1592919309.118389073]: Sending goal
[ERROR] [1592919309.132721803]: Failed to call update polygon service.
Warning: class_loader.ClassLoader: SEVERE WARNING!!! Attempting to unload library while objects created by this loader exist in the heap! You should delete your objects before attempting to unload the library or destroying the ClassLoader. The library will NOT be unloaded.
         at line 122 in /tmp/binarydeb/ros-melodic-class-loader-0.4.1/src/class_loader.cpp

turtlebot3_frontier_exploration.launch :

<launch>
  <!-- Arguments -->
  <arg name="model" default="$(env TURTLEBOT3_MODEL)" doc="model type [burger, waffle, waffle_pi]"/>
  <arg name="configuration_basename" default="turtlebot3_lds_2d.lua"/>
  <arg name="sensor_range" default="1.0"/>
  <arg name="cmd_vel_topic" default="/cmd_vel" />
  <arg name="odom_topic" default="odom" />

  <!-- TurtleBot3 and Gmapping -->
  <include file="$(find turtlebot3_slam)/launch/turtlebot3_gmapping.launch">
    <arg name="model" value="$(arg model)" />
  </include>

  <!-- AMCL -->
  <include file="$(find turtlebot3_navigation)/launch/amcl.launch"/>

  <!-- move_base -->
  <node pkg="move_base" type="move_base" respawn="false" name="move_base" output="screen">
    <param name="base_local_planner" value="dwa_local_planner/DWAPlannerROS" />
    <rosparam file="$(find turtlebot3_navigation)/param/costmap_common_params_$(arg model).yaml" command="load" ns="global_costmap" />
    <rosparam file="$(find turtlebot3_navigation)/param/costmap_common_params_$(arg model).yaml" command="load" ns="local_costmap" />
    <rosparam file="$(find turtlebot3_navigation)/param/local_costmap_params.yaml" command="load" />
    <rosparam file="$(find turtlebot3_navigation)/param/global_costmap_params.yaml" command="load" />
    <rosparam file="$(find turtlebot3_navigation)/param/move_base_params.yaml" command="load" />
    <rosparam file="$(find turtlebot3_navigation)/param/dwa_local_planner_params_$(arg model).yaml" command="load" />
    <remap from="cmd_vel" to="$(arg cmd_vel_topic)"/>
    <remap from="odom" to="$(arg odom_topic)"/>
  </node>

  <!-- frontier_exploration -->
  <node pkg="exploration_server" type="plugin_client" name="plugin_client" output="screen"/>
  <node pkg="exploration_server" type="exploration_server_node" name="exploration_server_node" output="screen" >
    <param name="frequency" type="double" value="1.0"/>
    <param name="goal_aliasing" type="double" value="$(arg sensor_range)"/>
    <rosparam file="$(find turtlebot3_navigation)/param/costmap_common_params_$(arg model).yaml" command="load" ns="explore_costmap" />
    <rosparam file="$(find turtlebot3_slam)/config/frontier_exploration.yaml" command="load" ns="explore_costmap" />
  </node>
</launch>