unknown error handler name 'rosmsg'

edit

I m trying the rosserial tutorials from the official site in ros melodic. While running the Serial_node.py I m getting this error :

[ERROR] [1598645013.553322]: Creation of publisher failed: unknown error handler name 'rosmsg'.

I m not even able to run basic serial examples. Please help.

The Serial_node.log:

[rospy.client][INFO] 2020-08-28 19:42:58,258: init_node, name[/serial_node], pid[13872]
[xmlrpc][INFO] 2020-08-28 19:42:58,258: XML-RPC server binding to 0.0.0.0:0
[xmlrpc][INFO] 2020-08-28 19:42:58,259: Started XML-RPC server [http://saurabh-Notebook:38231/]
[rospy.init][INFO] 2020-08-28 19:42:58,259: ROS Slave URI: [http://saurabh-Notebook:38231/]
[rospy.impl.masterslave][INFO] 2020-08-28 19:42:58,259: _ready: http://saurabh-Notebook:38231/
[xmlrpc][INFO] 2020-08-28 19:42:58,259: xml rpc node: starting XML-RPC server
[rospy.registration][INFO] 2020-08-28 19:42:58,260: Registering with master node http://localhost:11311
[rospy.init][INFO] 2020-08-28 19:42:58,359: registered with master
[rospy.rosout][INFO] 2020-08-28 19:42:58,372: initializing /rosout core topic
[rospy.rosout][INFO] 2020-08-28 19:42:58,376: connected to core topic /rosout
[rospy.simtime][INFO] 2020-08-28 19:42:58,379: /use_sim_time is not set, will not subscribe to simulated time [/clock] topic
[rosout][INFO] 2020-08-28 19:42:58,387: ROS Serial Python Node
[rosout][INFO] 2020-08-28 19:42:58,406: Connecting to /dev/ttyUSB0 at 115200 baud
[rosout][ERROR] 2020-08-28 19:42:58,413: Error opening serial: [Errno 13] could not open port /dev/ttyUSB0: [Errno 13] Permission denied: '/dev/ttyUSB0'
[rospy.internal][INFO] 2020-08-28 19:42:58,597: topic[/rosout] adding connection to [/rosout], count 0
[rosout][ERROR] 2020-08-28 19:43:01,420: Error opening serial: [Errno 13] could not open port /dev/ttyUSB0: [Errno 13] Permission denied: '/dev/ttyUSB0'
[rosout][ERROR] 2020-08-28 19:43:04,428: Error opening serial: [Errno 13] could not open port /dev/ttyUSB0: [Errno 13] Permission denied: '/dev/ttyUSB0'
[rosout][ERROR] 2020-08-28 19:43:07,437: Error opening serial: [Errno 13] could not open port /dev/ttyUSB0: [Errno 13] Permission denied: '/dev/ttyUSB0'
[rosout][ERROR] 2020-08-28 19:43:10,443: Error opening serial: [Errno 13] could not open port /dev/ttyUSB0: [Errno 13] Permission denied: '/dev/ttyUSB0'
[rosout][ERROR] 2020-08-28 19:43:13,451: Error opening serial: [Errno 13] could not open port /dev/ttyUSB0: [Errno 13] Permission denied: '/dev/ttyUSB0'
[rosout][ERROR] 2020-08-28 19:43:16,460: Error opening serial: [Errno 13] could not open port /dev/ttyUSB0: [Errno 13] Permission denied: '/dev/ttyUSB0'
[rospy.core][INFO] 2020-08-28 19:43:16,476: signal_shutdown [signal-2]
[rospy.internal][INFO] 2020-08-28 19:43:16,489: topic[/rosout] removing connection to /rosout
[rospy.impl.masterslave][INFO] 2020-08-28 19:43:16,490: signal-2
[rospy.core][INFO] 2020-08-28 19:43:16,601: signal_shutdown [atexit]
[rospy.client][INFO] 2020-08-28 19:44:02,719: init_node, name[/serial_node], pid[13906]
[xmlrpc][INFO] 2020-08-28 19:44:02,720: XML-RPC server binding to 0.0.0.0:0
[xmlrpc][INFO] 2020-08-28 19:44:02,720: Started XML-RPC server [http://saurabh-Notebook:36623/]
[rospy.init ...