Error while saving an attachment in servicenow table using REST and SAVE AN ATTACHMENT

[mdshahvez11]

{
    "Action Status": {
        "code": 1,
        "message": "Error encountered while creating Attachment. Record for file Changes on letters ALL.xlsx is not of required class."
    }
}

I'm getting attachments in href or in url and i'm using SAVE AS ATTACHMEMNTS way to save them with there respective record , but while runnig the flow i'm getting this error.