Hey @Rockylzh, thanks for reporting that. The server responds with a status code 429 (Too Many Requests), which for the time being the app doesn't handle correctly. In a future update it will properly treat this as an error. In the meantime, you can try removing the attachment that seems to doesn't open after the download, and try downloading again. You can do so by long tapping the item to get the context menu, and selecting the "Remove Download" action.