Telegram added "Group Topics" feature to the API. It works magically as channel comments feature: all messages as comments (or in the topic) will be added to the group as a reply to system message such a post from a channel or "Topic created" message.
This way Telegram is able to gather messages and change its view as a new feature, type or screen.
Error TOPIC_DELETED
I have a bot made for the Aurora Hunters community which helps to watch the solar activity. Before the update it was used in a big group chat as usual, but after conversion the group to a bunch of topics we have no ability to post messages to the main chat.
And if bot send a message just in a chat as always, you will get an error:
Error: ETELEGRAM: 400 Bad Request: failed to send message #1
with the error message "TOPIC_DELETED"
You have to add a message_thread_id param to message options to send in correctly in the topic.
const options = {};
if (msg.is_topic_message) {
options.message_thread_id = msg.message_thread_id;
}
bot.sendChatAction(chatId, 'upload_photo');
bot.sendMediaGroup(chatId, mediaGroup, options);