[QUESTION] How to check if a user block and stop bot

[bsimjoo]

How to check if a user block and stop bot

I use a database to store all users ids and information, and then my bot iterate users id and send message to them. But when a user block and stop bot I don't know how to remove user from database and bot will try to send message to a blocked user and this will raise an exception. I added a handler of type MessageHandler with Filters.update to check all update and I saw my bot does not receive any update when a user block and stop bot. so is there any other way except handling the exception?

Related part of your code

def log_update(u: Update, c:CallbackContext):
    message = (
        'Received a new update event from telegram\n'
        f'update = {json.dumps(u.to_dict(), indent = 2, ensure_ascii = False)}\n'
        f'user_data = {json.dumps(c.user_data, indent = 2, ensure_ascii = False)}\n'
        f'chat_data = {json.dumps(c.chat_data, indent = 2, ensure_ascii = False)}'
    )
    logging.info(message)
    if self.debug:
        try:
            self.bot.send_message(self.ownerID,html.escape(message), parse_mode = ParseMode.HTML)
        except Exception as e:
            self.log_bug(e,'Exception while sending update log to owner',ownerID=self.ownerID, message=html.escape(message))

self.dispatcher.add_handler(MessageHandler(Filters.update,log_update))

[Bibo-Joshi]

As of API 5.1 you will get an update with update.my_chat_member, where update.my_chat_member.new_chat_member.status can be used to check if the bot has been blocked. In PTB v13.4+ you can use ChatMemberHandler to catch those updates.
Nevertherless, handling exceptions is a very sane & advisable thing to do. IIRC Unauthorized is raised when the user has blocked the bot, but you can also check the exception message (str(e)) to see that.

[bsimjoo]

Can I use ChatMemberHandler to check if the bot is kicked out of a group or channel?

[Bibo-Joshi]

Yes. By comparing the old/new_chat_member_status you can infere what has happened