botframework get attachment api returns with 404 for old images
Solution 1:
It's important to note that the Azure Bot Service's Connector service is not a storage service. When attachments are sent to/thru the Connector, Azure will store the attachment for no more than 24 hours.
If you are needing to access attachments sent days/weeks/months ago, then you should utilize Azure Blob Storage, or some equivalent service, to meet those needs.