I’m developing a Telegram bot using the Telethon library. I’ve defined an event handler function to handle specific events in a Telegram channel. However, when a relevant event occurs, the event handler function doesn’t seem to execute as expected.

Here all code:

import asyncio
from telethon import TelegramClient, events
from telethon.tl.functions.channels import GetFullChannelRequest
from config import api_id, api_hash, phone_number, welcome_message

session_name = 'new_session'

async def main():
client = TelegramClient(session_name, api_id, api_hash)
await client.start(phone_number)

    try:
        channel = await client(GetFullChannelRequest('yaebav1010'))
        channel_id = channel.full_chat.id
    
        @client.on(events.ChatAction(chats=channel_id))
        async def handler(event):
            print(f"Event received: {event}")
            if event.user_added or event.user_joined:
                try:
                    new_user = await event.get_user()
                    user_id = new_user.id
                    print(f"New user joined: {new_user.username or new_user.id}")
    
                    await client.send_message(user_id, welcome_message)
                    print(f"Message sent to {new_user.username or new_user.id}")
                except Exception as e:
                    print(f"Failed to send message to {new_user.username or new_user.id}: {e}")
    
        print('Bot started...')
        while True:
            try:
                await client.run_until_disconnected()
            except Exception as e:
                if "Disconnect" in str(e):
                    print("Disconnected. Reconnecting...")
                    await asyncio.sleep(5)  # pause for 5 seconds before attempting to reconnect
                    await client.connect()
                    await client.start(phone_number)
    
    except Exception as e:
        print(f"Error occurred: {e}")

if __name__ == '__main__':
loop = asyncio.get_event_loop()
loop.run_until_complete(main())

I verified that the event handler function is correctly defined and registered.
I ensured that the necessary event is triggered in the Telegram channel.
I checked for any errors or exceptions thrown during the execution of the event handler function, but there are no apparent issues.

I expect the event handler function to execute whenever the specified event occurs in the Telegram channel, allowing me to perform the desired actions in response to the event.