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EWS Core event ids 5, 6, and 7 logged RRS feed

  • Question

  • Hi,

    We're running 2 Exchange 2013 CU20 servers on premise in a DAG, situated behind a pair of barracuda hardware load balancers. We use an external cloud based marketing/sales application that connects to Exchange's EWS site to compose and send email outbound.  This application also has meeting/calendar functionality that ties into Outlook calendars.

    what I've been noticing lately are hundreds of MSExchange Web Services warnings and errors being logged on both servers.

    example:

    A notification for subscription [HQBleGNoLTAxLmdyYXBoaWNwcm9kdWN0cy5sb2NhbBAAAACNt9GJgkPKT5eunEgmmthA/V1ATZA11ggQAAAA+GxcBMzPmUGzlhKKXzYAMg==] against endpoint [cloud provider domain]/ews/calendar/event_notifications?calendar=3&org=f83a0147-7ea4-4f02-998b-7c76adc90754&secret=68c3bf75d6620cfd] couldn't be sent. (Send attempts: 2) Details: WebException: The underlying connection was closed: An unexpected error occurred on a send. Status: SendFailure    at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
       at Microsoft.Exchange.Services.Core.NotificationServiceClient.HandleResponse(IAsyncResult responseAsyncResult)

    some of my research led me to some stack overflow forum posts describing similar event IDs (not exactly the same description) and that it could be related to an encryption protocol mismatch or usage of an obsoleted encryption protocol on one end of the communication. I'm thinking maybe the ASP .NET framework on exchange is using TLS 1.0 and the remote site isn't negotiating secure communication with Exchange properly because of this, but I can't appear to verify this.

    looking at this documentation https://blogs.technet.microsoft.com/exchange/2018/04/02/exchange-server-tls-guidance-part-2-enabling-tls-1-2-and-identifying-clients-not-using-it/

    and I was thinking that disabling TLS 1.0 within the registry on both exchange servers may help, but am unsure. (SSL 2.0 and 3.0 are disabled via the registry)

    any tips with anyone experiencing a similar issue would be welcome.



    • Edited by GP-Admin Friday, October 19, 2018 7:18 PM lol
    • Moved by Manu Meng Monday, October 22, 2018 5:59 AM relocate
    Friday, October 19, 2018 4:29 PM

Answers

  • For those interested,  I was able to resolve this by adding the following registry keys to our exchange servers to enable and force usage of the TLS protocols with the .Net framework

    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Client] Enabled set to 1  DisabledByDefault set to 0

    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Client] Enabled set to 1  DisabledByDefault set to 0

    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.0\Client] Enabled set to 1  DisabledByDefault set to 0

    [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v4.0.30319]
    "SystemDefaultTlsVersions"=dword:00000001 
    • Edited by GP-Admin Tuesday, November 6, 2018 6:46 PM
    • Marked as answer by GP-Admin Tuesday, November 6, 2018 6:46 PM
    Tuesday, November 6, 2018 6:45 PM

All replies

  • Hi,

    Welcome to the Exchange Server forum. This forum is for questions and feedback related to Exchange server. Since your question is more related to EWS which related with Exchange development, I'll move it to a more appropriate forum: https://social.technet.microsoft.com/Forums/office/en-US/home?forum=exchangesvrdevelopment

    Hope your get useful suggestion from that forum. 

    Regards,

    Kyle Xu


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

    Click here to learn more. Visit the dedicated forum to share, explore and talk to experts about Microsoft Teams.

    Monday, October 22, 2018 5:59 AM
  • For those interested,  I was able to resolve this by adding the following registry keys to our exchange servers to enable and force usage of the TLS protocols with the .Net framework

    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Client] Enabled set to 1  DisabledByDefault set to 0

    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Client] Enabled set to 1  DisabledByDefault set to 0

    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.0\Client] Enabled set to 1  DisabledByDefault set to 0

    [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v4.0.30319]
    "SystemDefaultTlsVersions"=dword:00000001 
    • Edited by GP-Admin Tuesday, November 6, 2018 6:46 PM
    • Marked as answer by GP-Admin Tuesday, November 6, 2018 6:46 PM
    Tuesday, November 6, 2018 6:45 PM