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Released: August 2026 Exchange Server Security Updates

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The_Exchange_Team
Platinum Contributor
Aug 11, 2026
Microsoft has released Security Updates (SUs) for vulnerabilities found in: Exchange Server Subscription Edition (SE) Exchange Server 2019 Exchange Server 2016 SUs are available for the f...
Updated Sep 08, 2026
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tylerdami's avatar
tylerdami
Copper Contributor
Aug 13, 2026

We found that after the July updates, our Exchange management accounts needed mailboxes associated or EPC threw a continuous error that prevented us from using the console. Is that a new known dependency? Thanks! 

Nino_Bilic's avatar
Nino_Bilic
Icon for Microsoft rankMicrosoft
Aug 13, 2026

I must say that I do not really understand what the problem is that you are having. Can you explain this scenario? What is the error?

  • tylerdami's avatar
    tylerdami
    Copper Contributor
    Aug 24, 2026

    Hey Nino, the issue was when we logged into ECP after the upgrade with our admin account, we received a continuous popup that would not allow us to click anything. On the event viewer side, we received this error: 

    Current user: 'REDACTED'
Web service call 'https://REDACTED:444/ecp/DDI/DDIService.svc/GetObject?ActivityCorrelationID=5850077c-6a3b-dc8c-bc2e-6c9d8901bcbb&workflow=GetForSDO&schema=DistributionGroups&msExchEcpCanary=VWZ9bOdNHESSe-_6OifEOBAydrKS-N4I9bN-LsvaD6G8aUA3th6rOPBClofLoRx1Tue7rlOAAfc.(https://REDACTED/ecp/DDI/DDIService.svc/GetObject?ActivityCorrelationID=5850077c-6a3b-dc8c-bc2e-6c9d8901bcbb&workflow=GetForSDO&schema=DistributionGroups&msExchEcpCanary=VWZ9bOdNHESSe-_6OifEOBAydrKS-N4I9bN-LsvaD6G8aUA3th6rOPBClofLoRx1Tue7rlOAAfc.)' failed with the following error:
System.ServiceModel.Dispatcher.NetDispatcherFaultException: The formatter threw an exception while trying to deserialize the message: There was an error while trying to deserialize parameter ECP:identity. The InnerException message was 'There was an error deserializing the object of type Microsoft.Exchange.Management.ControlPanel.Identity. End element 'RawIdentity' from namespace '' expected. Found element 'type' from namespace ''.'.  Please see InnerException for more details. ---> System.Runtime.Serialization.SerializationException: There was an error deserializing the object of type Microsoft.Exchange.Management.ControlPanel.Identity. End element 'RawIdentity' from namespace '' expected. Found element 'type' from namespace ''. ---> System.Xml.XmlException: End element 'RawIdentity' from namespace '' expected. Found element 'type' from namespace ''.
   at System.Xml.XmlExceptionHelper.ThrowXmlException(XmlDictionaryReader reader, String res, String arg1, String arg2, String arg3)
   at System.Xml.XmlExceptionHelper.ThrowEndElementExpected(XmlDictionaryReader reader, String localName, String ns)

    To stop this from happening, we needed to mailbox enable our Exchange Admin accounts. This corrected the issue. 

    • Nino_Bilic's avatar
      Nino_Bilic
      Icon for Microsoft rankMicrosoft
      Aug 25, 2026

      Please have a look at this: HTTP server error status (500) when signing in to EAC - Exchange | Microsoft Learn basically - you might have an issue with the Arbitration Mailbox (which is used in case the amdin does not have a mailbox).

      Additional thing - please make sure that the server that has the arbitration mailbox has also been updated.

      If all of that doe snot solve the problem, please open a ticket (we cannot repro this problem as of now).