UnableToDeserializePostBody error when testing with the exact example from documentation

Question

Hi,

I want to create a message using MIME format, using the example from page https://learn.microsoft.com/en-us/graph/outlook-send-mime-message#specify-request-header-and-mime-message-body, I get a 400 result with error
{"error":{"code":"UnableToDeserializePostBody","message":"were unable to deserialize "}}
What I know so far is that the message is correctly base 64 formatted (I use the base 64 string from the example), content-type is set to text/plain.
Is there any way to have more details about the failure?
Did anyone have a similar issue?
I’m out of ideas .'(

Thanks.

Answer 1

I was getting the same error with /me/messages. This is how my request looked like with python:

   body = {  
       "message": {  
           "subject": "test subject",  
           "body": {  
               "contentType": "HTML",  
               "content": "test content"  
           },  
           "toRecipients": [{  
               "emailAddress": {  
                   "address": "******@somewhere.com"  
               }}]  
       }  
   }  
     
   response = requests.post(create_mail_url, data=json.dumps(body), headers=headers)  

Strangly this works fine with /me/sendMail but when calling /me/messages it was necessary to remove the outer object with body["message"]. This mans that in case of a json message the body is different. Your link points to send-message, I think you should take a look at this page https://learn.microsoft.com/en-us/graph/api/user-post-messages?view=graph-rest-1.0&tabs=http that discribes the format for create-message. There might be similar differences for mime.

Answer 2

Note that this fails when specifying a mailFolder only:

• A request such as POST /users/{id|userPrincipalName}/messages works
• But POST /users/{id|userPrincipalName}/mailFolders/{id}/messages fails