I’m using BotFramework in C#. The issue I’m encountering is that when I upload an attachment from Teams with certain characters, such as a ‘+’, the attachment “disappears” when received in the bot’s backend.

For example, if I upload a file with a “normal” name like test.txt, I receive this in the bot’s backend:

{
    "attachments": [
        {
            "contentType": "application/vnd.microsoft.teams.file.download.info",
            "content": {
                "downloadUrl": "https://ckm-my.sharepoint.com/personal/xxxxxx/_layouts/15/download.aspx?UniqueId=xxxxx-xxxx-xxxx-xxxx-xxxxx&Translate=false&tempauth=v1.xxxx.xxxx.xxxx&ApiVersion=2.0",
                "uniqueId": "xxxx-xxxx-xxxx-xxxx-xxxxx",
                "fileType": "txt"
            },
            "contentUrl": "https://ckm-my.sharepoint.com/personal/xxxxxx/Documents/Microsoft Teams Chat Files/test.txt",
            "name": "test.txt"
        },
        {
            "contentType": "text/html",
            "content": ""
        }
    ],
    "type": "message",
    "timestamp": "2024-07-11T10:29:11.4680572Z",
    "localTimestamp": "2024-07-11T12:29:11.4680572+02:00",
    "id": "1720693751445",
    "channelId": "msteams",
    // ....
}

However, if I upload a file with a name like test+.txt, I receive only this:

{
    "attachments": [
        {
            "contentType": "text/html",
            "content": ""
        }
    ],
    "type": "message",
    "timestamp": "2024-07-11T10:36:45.0287287Z",
    "localTimestamp": "2024-07-11T12:36:45.0287287+02:00",
    "id": "1720694205007",
    "channelId": "msteams",
    //...
}

This issue occurs with the basic example from BotBuilder-Samples (https://github.com/microsoft/BotBuilder-Samples/tree/main/samples/csharp_dotnetcore/15.handling-attachments).

It seems attachments with certain characters in their names are not being processed correctly. Any insights on how to handle this would be greatly appreciated.