AttributeError: 'NoneType' object has no attribute 'recv' while running the sub_file.py

Question

when I run the sub_file.py program there is an error like this :

AttributeError: 'NoneType' object has no attribute 'recv'

this is the sub_file.py code:

import time
import paho.mqtt.client as mqtt #import the client1
import base64

broker_address="mqtt.eclipseprojects.io"

port = 1883
client = mqtt.Client("P2") #create new instance

client.connect(broker_address,port) #connect to broker

def on_message(cln, obj, msg):
  print("new message")
  data = msg.payload.decode()
  msg = str(data)
  img = msg.encode('ascii')
  with open('iris.jpg', 'wb') as fd:
    final_data = base64.b64decode(img)
    fd.write(final_data)
    fd.close()

def on_subscribe(client, userdata, mid, granted_qos):
  print("subscribe success")

client.subscribe("photo_topic_file")


client.on_subscribe = on_subscribe
print("Subscribing...")
client.loop_start()

client.on_message = on_message

client.loop_forever()

and this the pub_file.py code:

import paho.mqtt.client as mqtt
import base64
import time

broker_address="mqtt.eclipseprojects.io"

port = 1883
client = mqtt.Client("P1")


f = open("data.jpg", "rb")
isi_file = f.read()
convert_result_ke_base64 = base64.b64encode(isi_file)


client.connect(broker_address, port)
client.loop_start()
result = client.publish("photo_topic_file", convert_result_ke_base64)

if result[0] == 0:
    print("publish success")
else:
    print("publish failed")
    
time.sleep(5)
client.loop_stop()

when i run the pub_file.py the program worked properly but when i run the sub_file.py it show the error

can someone fix this problem?

Answer 1

client.on_subscribe = on_subscribe
print("Subscribing...")
client.loop_start()

client.on_message = on_message

client.loop_forever()

You are starting two message loops:

• One with client.loop_start()
• The other with client.loop_forever()

This causes issues because the code is written with an assumption that only one message loop will be running.

The simplest way to resolve this is to remove the client.loop_start().

Note that it's probably better to call subscribe from on_connect as shown in "Getting Started". I would also suggest setting the callbacks before you call connect (setting on_message after starting the loop could, potentially, lead to message loss).