sendMessage with "message_thread_id=1" returns "BadRequest: Message thread not found"

[gerkatheking]

this is the original report from another person https://github.com/python-telegram-bot/python-telegram-bot/issues/4739#issue-2959833823

it is impossible to "reply in another chat" using sendMessage when destination is general topic of the chat. if you set message_thread_id 1 => 400 message thread not found if you don't specify message_thread_id it replies in the source thread of reply_to_message_id message.

[levlam]

Does the forum chat have more than 1 million messages?

[gerkatheking]

No, It reproduces in empty chat.

[levlam]

Are you sure that the chat is a forum chat?

[gerkatheking]

yes and sendMessage response has "is_forum": true