upgraded_from_basic_group_id -> Chat not found

[leoMehlig]

When I attempt to load the chat history of a supergroup prior to it's upgrade from a basic group (using the upgraded_from_basic_group_id and the upgraded_from_max_message_id), I get an error:
code: 6
message: Chat not found

Do I misunderstand the use if those fields?
As I understand it: To get message from the supergroup from before the upgrade, I have to request messages from the basic group.

[levlam]

You are right. Field upgraded_from_basic_group_id contains a basic group identifier, which needs to be passed first to createBasicGroupChat to receive corresponding chat. Then you can get messages history in the chat through getChatHistory.

[leoMehlig]

Ok thank you. Wasn't clear to me chat I have to create this chat first.