Intermittent Empty MDN Response From AS2 Send RRS feed

  • Question

  • We are having some trouble with AS2 communications with one particular trading partner. None of the others seem to have this issue. However, they're an important customer so we're diligently trying to track this down.

    The manifestation of the problem is, occasionally when we send an EDI file to their AS2 server we receive the following error from BizTalk:

    An AS2 message was received that did not contain the AS2-From header

    I have captured the traffic back and forth using Fiddler, and here's what I see.

    POST http://<their AS2 server URL>
    Content-Type: application/pkcs7-mime; smime-type=enveloped-data; name="smime.p7m"
    AS2-Version: 1.2
    Content-Transfer-Encoding: binary
    Mime-Version: 1.0
    EDIINT-Features: multiple-attachments
    AS2-To: <Their AS2-To ID>
    Message-ID: <The BTS ID of the transaction>
    AS2-From: <Our AS2-From ID>
    Disposition-Notification-To: <email address of admin>
    User-Agent: Microsoft (R) BizTalk (R) Server 2013 R2
    Host: <URL of partner AS2 server, w/o HTTP>
    Content-Length: 3360
    Expect: 100-continue
    Connection: Close

    -- Followed by encrypted binary data for the MIME attachment that constitutes the body of the transaction.

    And the response we received was:
    HTTP/1.1 200 OK
    Connection: close

    So you can see that we're not getting the rest of the AS2 headers that were expected. 

    The really strange part is that this only happens about 30% of the time! If I queue up 10 transaction files, 7 will send properly and receive MDNs and 3 will not.

    What makes it even more strange is that they see the same thing intermittently when they send to us!

    Can anyone offer a suggestion regarding how to determine what the cause is? It would seem like something low-level in the plumbing. Perhaps in IIS?

    Other than using the proxy, I'm stuck regarding what to try next.


    Bob Mc.

    Friday, May 13, 2016 5:35 PM

All replies

  • Hi Bob,

    According to the error message above, it might be wrong certificate issue for an AS2 party, and your partner cannot decode/decrypt the message, etc.

    Please check the points mentioned in the thread below:

    AS2 Synchronus Empty MDN

    hope it helps.



    We are trying to better understand customer views on social support experience, so your participation in this interview project would be greatly appreciated if you have time. Thanks for helping make community forums a great place.
    Click HERE to participate the survey.

    • Proposed as answer by Angie Xu Monday, May 30, 2016 6:05 AM
    • Marked as answer by Angie Xu Monday, May 30, 2016 6:05 AM
    • Unmarked as answer by BobMc98 Monday, May 30, 2016 5:35 PM
    • Unproposed as answer by BobMc98 Monday, May 30, 2016 5:42 PM
    Saturday, May 21, 2016 3:24 AM
  • Thanks for the reply Angie.

    Unfortunately, I'm pretty certain that this is not a certificate issue. I've dealt with quite a few of those during the course of this rollout so I'm familiar with the symptoms. Also, the AS2 communications do work about 70% of the time with this trading partner, as I noted in my original post, so if there was a certificate problem wouldn't it always fail?

    The thread you linked was one of the first resources I came across with a similar issue, and I reviewed it thoroughly before posting here. I had already traced the communication with Fiddler, as I noted in my original post, and included the results therein. As you can see, we're just not getting the requisite AS2 headers and body in the reply. But this only happens some of the time. Strange.

    This is still an open issue, just like the situation in the thread you referenced, and my client has had to revert back to a third party EDI provider at significant cost.

    Any other ideas would be appreciated.

    Bob Mc.

    Monday, May 30, 2016 5:42 PM