Exchange 2019 Mitigation service error 1008

Dmitry Horushin 61 Reputation points

I regularly receive error 1008
Exception encountered while fetching mitigations : System.Exception: This XML is not deemed safe to consume since Response xml's signing cert is invalid or not from microsoft

The issue started June 9.

Any suggestions?

King regards,

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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Accepted answer
  1. Andy David - MVP 133.4K Reputation points MVP
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4 additional answers

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  1. Luis Rodriguez 6,156 Reputation points Microsoft Employee

    Hello @Dmitry Horushin

    Welcome to Microsoft Q&A Platform,

    Please refer to the thread below as it's related to the same scenario:

    I hope this helps!


    Please don’t forget to "Accept the answer" and “up-vote” wherever the information provided helps you, this can be beneficial to other community members.

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  2. Joyce Shen - MSFT 16,576 Reputation points

    Hi @Luis Rodriguez

    Yes, Event 1008 with the same source will be logged for any errors that are encountered, such as when the EM service cannot reach the OCS(Office Config Service).

    Ensure that your Exchange servers can communicate with the Internet to validate the certificate chain.

    simulate the behaviour of the EEMS by getting the test page with a browser ( For those of you not being familiar - look at the schema links in the XML document as well as the certificate of the URL and check all the certificate chaining, revocation lists URLs and so on.
    For the IPs compare the blocked IPs with the following networks and allow them:

    If an Answer is helpful, please click "Accept Answer" and upvote it.

    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

  3. Dmitry Horushin 61 Reputation points

    Thank you for your answers and questions.

    1) Error 1008 appears every hour on all Exchange servers.
    2) There is no problems to connect to
    Browsers on all servers return the same answer. I think that it's something wrong with the signature as it's described on the reference of @nak

    Best regards,

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  4. Dmitry Horushin 61 Reputation points

    Hi, Andy.
    Thank you for providing details.
    Now the issue is resolved.
    Have a nice day!

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