ImportError: cannot import name 'JointLimits' from 'moveit_msgs.msg' (unknown location)

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Hi,

I am trying to run the start_training_v2.launch but getting the error ImportError: cannot import name 'JointLimits' from 'moveit_msgs.msg' (unknown location). I have installed MoveIt using the command sudo apt install ros-noetic-moveit and installation process finished cleanly. I am using Ubuntu 20.04. Can you please help me out resolving the problem? Thank you in advance.

The complete error message is given below for your reference,

roslaunch iriwam_openai_ros_example start_training_v2.launch 
... logging to /home/user/.ros/log/59c99942-811f-11eb-9c9d-fdbc231597b5/roslaunch-user-ai-21285.log
Checking log directory for disk usage. This may take a while.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

started roslaunch server http://user-ai:46149/

SUMMARY
========

PARAMETERS
* /iriwam/alpha: 0.1
* /iriwam/epsilon: 0.9
* /iriwam/epsilon_discount: 0.999
* /iriwam/gamma: 0.7
* /iriwam/nepisodes: 500
* /iriwam/nsteps: 10000
* /iriwam/ros_ws_abspath: /home/user/simula...
* /iriwam/task_and_robot_environment_name: IriWamTcpToBowl-v0
* /rosdistro: noetic
* /rosversion: 1.15.9

NODES
  /
    iriwam_tcp_to_bowl_qlearn (iriwam_openai_ros_example/start_qlearning_v2.py)

auto-starting new master
process[master]: started with pid [21293]
ROS_MASTER_URI=http://localhost:11311

setting /run_id to 59c99942-811f-11eb-9c9d-fdbc231597b5
process[rosout-1]: started with pid [21303]
started core service [/rosout]
process[iriwam_tcp_to_bowl_qlearn-2]: started with pid [21310]
[DEBUG] [1615325722.559839]: init_node, name[/iriwam_tcp_to_bowl_qlearn], pid[21310]
[DEBUG] [1615325722.560875]: binding to 0.0.0.0 0
[DEBUG] [1615325722.561654]: bound to 0.0.0.0 44647
[DEBUG] [1615325722.562550]: ... service URL is rosrpc://user-ai:44647
[DEBUG] [1615325722.563308]: [/iriwam_tcp_to_bowl_qlearn/get_loggers]: new Service instance
[DEBUG] [1615325722.564623]: ... service URL is rosrpc://user-ai:44647
[DEBUG] [1615325722.565335]: [/iriwam_tcp_to_bowl_qlearn/set_logger_level]: new Service instance
[WARN] [1615325722.567105]: Env: IriWamTcpToBowl-v0 will be imported
Traceback (most recent call last):
  File "/home/user/simulation_ws/src/openai_examples_projects/iriwam_openai_ros_example/scripts/start_qlearning_v2.py", line 22, in <module>
    env = StartOpenAI_ROS_Environment(
  File "/home/user/simulation_ws/src/openai_ros/openai_ros/src/openai_ros/openai_ros_common.py", line 26, in StartOpenAI_ROS_Environment
    result = RegisterOpenAI_Ros_Env(task_env=task_and_robot_environment_name,
  File "/home/user/simulation_ws/src/openai_ros/openai_ros/src/openai_ros/task_envs/task_envs_list.py", line 119, in RegisterOpenAI_Ros_Env
    from openai_ros.task_envs.iriwam import tcp_to_bowl
  File "/home/user/simulation_ws/src/openai_ros/openai_ros/src/openai_ros/task_envs/iriwam/tcp_to_bowl.py", line 4, in <module>
    from openai_ros.robot_envs import iriwam_env
  File "/home/user/simulation_ws/src/openai_ros/openai_ros/src/openai_ros/robot_envs/iriwam_env.py", line 14, in <module>
    from moveit_msgs.msg import JointLimits
ImportError: cannot import name 'JointLimits' from 'moveit_msgs.msg' (unknown location)
[iriwam_tcp_to_bowl_qlearn-2] process has died [pid 21310, exit code 1, cmd 
/home/user/simulation_ws/src/openai_examples_projects/iriwam_openai_ros_example/scripts/start_qlearning_v2.py 
__name:=iriwam_tcp_to_bowl_qlearn __log:=/home/user/.ros/log/59c99942-811f-11eb-9c9d-fdbc231597b5/iriwam_tcp_to_bowl_qlearn-2.log].
log file: /home/user/.ros/log/59c99942-811f-11eb-9c9d-fdbc231597b5/iriwam_tcp_to_bowl_qlearn-2*.log