Graph API sendMail - The property 'contentBytes' does not exist on type 'microsoft.graph.attachment'.

Question

We are using HTTP for user: sendMail following the example at https://learn.microsoft.com/en-us/graph/api/user-sendmail?view=graph-rest-1.0&tabs=http:

The error message correctly asserts that

The property 'contentBytes' does not exist on type 'microsoft.graph.attachment'.

However, the data type in the Mail JSON object is fileAttachment, not attachment. The reference for fileAttachment clearly shows "contentBytes" as a property "fileAttachment resource type". Am I missing something? Thank you.

Response

{"error": {
    "code": "RequestBodyRead",
    "message": "The property 'contentBytes' does not exist on type 'microsoft.graph.attachment'. Make sure to only use property names that are defined by the type or mark the type as open type."
}}

HTTP POST

POST https://graph.microsoft.com/v1.0/me/sendMail 
Content-type: application/json

{
    "saveToSentItems": "false",
    "message": {
        "toRecipients": [
            {"emailAddress": {"address": "example1@example.com"}},
            {"emailAddress": {"address": "example2@example.com"}}
        ],
        "attachments": [
            {
                "name": "attachment-1.txt",
                "contentBytes": "QXR0YWNobWVudCBPbmUgLQpUaGlzIGlzIGEgdGVzdCBzZW5kIGZyb20gT25lTWUuCgoKCk9uZU1lIExMQy4KUC5PLiBCb3ggMjI1NzIKSG91c3RvbiBUWCA3NzIyNw==",
                "contentType": "text/plain",
                "@data.type": "#microsoft.graph.fileAttachment"
            },
            {
                "name": "attachment-2.txt",
                "contentBytes": "QXR0YWNobWVudCBUd28gLQpUaGlzIGlzIGEgdGVzdCBzZW5kIGZyb20gT25lTWUuCgoKCk9uZU1lIExMQy4KUC5PLiBCb3ggMjI1NzIKSG91c3RvbiBUWCA3NzIyNw==",
                "contentType": "text/plain",
                "@data.type": "#microsoft.graph.fileAttachment"
            }
        ],
        "subject": "2023-08-30 15:23:30.843 - Microsoft Graph Email with Attachment Test",
        "bccRecipients": [],
        "ccRecipients": [],
        "body": {
            "contentType": "Text",
            "content": "This is the test email body."
        },
        "hasAttachments": true
    }
}

Answer 1

The issue was missing the 'o' in the key ""@data.type" in the key:value pair "@data.type": "#microsoft.graph.fileAttachment". The correct key is "@odata.type" so k:v -> "@odata.type": "#microsoft.graph.fileAttachment"

Credit StackOverflow https://stackoverflow.com/questions/77010710/ms-graph-api-error-contentbytes-not-a-property-of-type-microsoft-graph-attachm/77012257#77012257

        "attachments": [
            {
                "name": "attachment-1.txt",
                "contentBytes": "QXR0YWNobWVudCBPbmUgLQpUaGlzIGlzIGEgdGVzdCBzZW5kIGZyb20gT25lTWUuCgoKCk9uZU1lIExMQy4KUC5PLiBCb3ggMjI1NzIKSG91c3RvbiBUWCA3NzIyNw==",
                "contentType": "text/plain",
                "@odata.type": "#microsoft.graph.fileAttachment"
            },
            {
                "name": "attachment-2.txt",
                "contentBytes": "QXR0YWNobWVudCBUd28gLQpUaGlzIGlzIGEgdGVzdCBzZW5kIGZyb20gT25lTWUuCgoKCk9uZU1lIExMQy4KUC5PLiBCb3ggMjI1NzIKSG91c3RvbiBUWCA3NzIyNw==",
                "contentType": "text/plain",
                "@odata.type": "#microsoft.graph.fileAttachment"
            }
        ],

Answer 2

Hello Ted Spradley,
Thank you for reaching out to this Q&A Forum.
When creating a file attachment, the correct format is "@odata.type": "#microsoft.graph.fileAttachment"
which you need to add in the request body. Please replace your body to;-

"attachments": [
            {
                "name": "attachment-1.txt",
                "contentBytes": "QXR0YWNobWVudCBPbmUgLQpUaGlzIGlzIGEgdGVzdCBzZW5kIGZyb20gT25lTWUuCgoKCk9uZU1lIExMQy4KUC5PLiBCb3ggMjI1NzIKSG91c3RvbiBUWCA3NzIyNw==",
                "contentType": "text/plain",
                "@odata.type": "#microsoft.graph.fileAttachment"
            }

Hope this helps.

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