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OWA issue after installing Exchange 2010 SP2 and RU6 RRS feed

  • Question

  • Hi,

    We're having a problem using OWA after patching our Exchange 2010 servers from SP1 RU7 to SP2 RU6.  The Exchange servers are running on Windows Server 2008 and are VMWare machines.  We can log into OWA and can see the emails.  But when we do anything (ie. open an email, create an email, etc.) we get the error message, "A problem occurred while you were trying to use your mailbox".  This doesn't happen all the time for all users.  Some users see it consistently.  Others see it sometimes but pretty frequently.  On the mailbox server there is a corresponding event logged in the Application log.  It's a 9646 error.  See below.  Any ideas on how to resolve?

    Thanks,

    Jeff


    Log Name:      Application
    Source:        MSExchangeIS
    Date:          8/28/2013 10:26:30 AM
    Event ID:      9646
    Task Category: General
    Level:         Error
    Keywords:      Classic
    User:          N/A
    Computer:      MailboxSvr.company.com
    Description:
    Mapi session "44da0bb7-e8d1-4a52-b15d-0c6ba7f276b3: /o=Company/ou=Loc/cn=Recipients/cn=user" exceeded the maximum of 16 objects of type "session".


    • Edited by jeffmar Wednesday, August 28, 2013 5:44 PM Correction
    Wednesday, August 28, 2013 5:42 PM

Answers

  • Hi Rebecca,

    Thanks again for your response.

    I opened a case with Microsoft support and they resolved the issue.  They had me change the OWA web.config file on the internet facing CAS server.  The default location is <drive>\Program Files\Microsoft\Exchange Server\<version>\ClientAccess\Owa.  Specifically, we changed the requireSSL to "false" for the httpOnlyCookies="false" requireSSL="true" domain="" parameter.  Then we removed all of the http redirection for the Default Web Site as well as for the AutoDiscover, EWS, OWA, and ECP Virtual directories.

    Once those changes were made then OWA was working again and there were no more 9646 errors either.

    Regards,

    Jeff

    • Marked as answer by jeffmar Tuesday, September 3, 2013 7:59 PM
    Tuesday, September 3, 2013 7:58 PM

All replies

  • Wednesday, August 28, 2013 6:14 PM
  • Hi Candeev,

    Yes, I saw that KB article already.  It is proposing increasing the number of sessions but that doesn't appear to be the best resolution.  The NOTE in the article even points to a warning that increasing the number of sessions could slow performance.  Plus, the article is referring to POP3 and IMAP4.  In this case it is OWA.  The bigger question is what was changed with SP2 and RU6 that would cause more sessions to be needed.  Thanks for the article though.

    Regards,

    Jeff

    Wednesday, August 28, 2013 6:53 PM
  • Hi Jeff,

    The number of sessions in the error message is used to prevent a single client from exhausting resource on Exchange Server. Event 9646 indicates that there are too many objects left open on the server.

    There are many causes for this issue and each cause we need further investigation:

    1.Use the command below to check if there are any old connections still active as well(run for several users and figure out the same features):

    Get-LogonStatistics username | ft LogonTime,LastAccessTime,ClientName,ApplicationId -AutoSize

    2.Try add the registry "Maximum Allowed Sessions per User" DWORD Value and double the Decimal value. The method is as the same as this KB turns out: http://support.microsoft.com/kb/980049/en-us .

    3.Check if the throttling policy is set properly. For your reference: Set-ThrottlingPolicy .

    Get-ThrottlingPolicy | select OWA*

    4.Verify the redirection is configured correctly if it exists.

    Feel free to tell me if you need more assistance.

    Regards,

    Rebecca

    • Proposed as answer by Sourabh Kumar Jha Thursday, August 29, 2013 12:43 PM
    • Unproposed as answer by jeffmar Thursday, August 29, 2013 2:11 PM
    Thursday, August 29, 2013 6:40 AM
  • Hi Rebecca,

    Thanks for your detailed answer.  As I mentioned to Candeev, the KB article does have a caveat in the NOTE that server performance could be adversely affected.

    Note The registry value Maximum Allowed Service Sessions Per User affects all Mailbox Databases on the server and is not applied on a per-user basis. If you increase this value, server performance may be adversely affected. For example, doubling the number of service sessions from 16 to 32 could slow server performance.

    I tried the Get-LogonStatistics command and while there does appear to be older connections still active, it doesn't seem to count against any OWA connections because the other ones are RPC ones or a type of Client=CI (what is that by the way?).  See the output below for before an OWA connection is made and for after an OWA connection is made.

    LogonTime LastAccessTime ClientName ApplicationId
    --------- -------------- ---------- -------------
    8/29/2013 8:46:44 AM 8/29/2013 8:56:43 AM JMail02 Client=CI
    8/29/2013 8:52:42 AM 8/29/2013 8:53:47 AM JMail10 Client=CI
    8/29/2013 8:41:45 AM 8/29/2013 8:55:07 AM JMail01 Client=CI
    8/29/2013 8:51:59 AM 8/29/2013 8:54:36 AM JMail09 Client=CI
    8/29/2013 8:52:42 AM 8/29/2013 8:54:55 AM JMail09 Client=CI
    8/29/2013 8:53:31 AM 8/29/2013 8:54:50 AM JMail08 Client=CI
    8/29/2013 8:23:33 AM 8/29/2013 8:24:22 AM JMail09 Client=CI
    8/29/2013 8:52:42 AM 8/29/2013 8:53:47 AM JMail02 Client=CI
    8/29/2013 8:46:46 AM 8/29/2013 8:54:47 AM JMail10 Client=CI
    8/29/2013 8:52:43 AM 8/29/2013 8:52:50 AM JMail07 Client=MSExchangeRPC
    8/29/2013 8:51:58 AM 8/29/2013 8:54:20 AM JMail08 Client=CI
    8/29/2013 8:51:58 AM 8/29/2013 8:54:47 AM JMail10 Client=CI
    8/29/2013 8:51:59 AM 8/29/2013 8:54:20 AM JMail08 Client=CI
    8/29/2013 8:53:30 AM 8/29/2013 8:54:55 AM JMail09 Client=CI
    8/29/2013 8:53:30 AM 8/29/2013 8:54:25 AM JMail09 Client=CI
    8/29/2013 8:53:30 AM 8/29/2013 8:57:25 AM JMail09 Client=CI
    8/29/2013 8:53:31 AM 8/29/2013 8:55:07 AM JMail01 Client=CI
    8/29/2013 8:53:31 AM 8/29/2013 8:54:47 AM JMail10 Client=CI
    8/29/2013 8:53:31 AM 8/29/2013 8:54:47 AM JMail10 Client=CI
    8/29/2013 8:53:31 AM 8/29/2013 8:54:47 AM JMail02 Client=CI
    8/29/2013 8:53:31 AM 8/29/2013 8:57:35 AM JMail08 Client=CI
    8/29/2013 8:53:49 AM 8/29/2013 8:54:50 AM JMail08 Client=CI
    8/29/2013 8:53:49 AM 8/29/2013 8:54:20 AM JMail08 Client=CI
    8/29/2013 8:53:50 AM 8/29/2013 8:56:44 AM JMail10 Client=CI

    Thursday, August 29, 2013 1:44 PM
  • Sorry, hit the wrong button.  Here's the rest of my response.

    This is the after OWA connection:

    LogonTime LastAccessTime ClientName ApplicationId
    --------- -------------- ---------- -------------

    8/29/2013 8:53:50 AM 8/29/2013 8:57:48 AM JMail10 Client=CI
    8/29/2013 8:46:44 AM 8/29/2013 8:57:47 AM JMail02 Client=CI
    8/29/2013 8:52:42 AM 8/29/2013 8:53:47 AM JMail10 Client=CI
    8/29/2013 8:53:31 AM 8/29/2013 8:54:47 AM JMail10 Client=CI
    8/29/2013 8:52:42 AM 8/29/2013 8:54:55 AM JMail09 Client=CI
    8/29/2013 8:53:31 AM 8/29/2013 8:57:35 AM JMail08 Client=CI
    8/29/2013 8:23:33 AM 8/29/2013 8:24:22 AM JMail09 Client=CI
    8/29/2013 8:52:42 AM 8/29/2013 8:53:47 AM JMail02 Client=CI
    8/29/2013 8:52:43 AM 8/29/2013 8:52:50 AM JMail07 Client=MSExchangeRPC
    8/29/2013 9:00:56 AM 8/29/2013 9:00:56 AM JMail07 Client=OWA
    8/29/2013 9:00:53 AM 8/29/2013 9:00:53 AM JMail07 Client=OWA
    8/29/2013 9:00:53 AM 8/29/2013 9:00:54 AM JMail07 Client=OWA
    8/29/2013 9:00:54 AM 8/29/2013 9:00:54 AM JMail07 Client=OWA
    8/29/2013 9:00:55 AM 8/29/2013 9:00:55 AM JMail07 Client=OWA
    8/29/2013 9:00:55 AM 8/29/2013 9:00:55 AM JMail07 Client=OWA
    8/29/2013 9:00:55 AM 8/29/2013 9:00:55 AM JMail07 Client=OWA
    8/29/2013 9:00:55 AM 8/29/2013 9:00:55 AM JMail07 Client=OWA
    8/29/2013 9:00:55 AM 8/29/2013 9:00:55 AM JMail07 Client=OWA
    8/29/2013 9:00:55 AM 8/29/2013 9:00:55 AM JMail07 Client=OWA
    8/29/2013 9:00:55 AM 8/29/2013 9:00:55 AM JMail07 Client=OWA
    8/29/2013 9:00:56 AM 8/29/2013 9:00:56 AM JMail07 Client=OWA
    8/29/2013 9:00:56 AM 8/29/2013 9:00:56 AM JMail07 Client=OWA
    8/29/2013 9:00:56 AM 8/29/2013 9:00:56 AM JMail07 Client=OWA
    8/29/2013 9:00:56 AM 8/29/2013 9:00:56 AM JMail07 Client=OWA
    8/29/2013 9:00:56 AM 8/29/2013 9:00:56 AM JMail07 Client=OWA

    Note, there are 16 OWA connections in addition to the RPC and CI ones.

    This is what we have for the throttling policies.

                OWAMaxConcurrency            OWAPercentTimeInAD           OWAPercentTimeInCAS    OWAPercentTimeInMailboxRPC
                -----------------            ------------------           -------------------    --------------------------
                                5                            30                           150                           150
                                5
                                5
                                5
                                5                            30                           150                           150
                                5                            30                           150                           150

    This is what we have for the HTTP redirect.


    • Edited by jeffmar Thursday, August 29, 2013 1:53 PM edit
    Thursday, August 29, 2013 1:52 PM
  • Also, nothing changed with the max sessions so why would it be using more connections?  One other change I forgot to mention besides the SP2 and RU6 upgrades was the creation of a CAS array.  We did not have a CAS array prior to this.  Could that account for increased OWA sessions?
    Thursday, August 29, 2013 2:19 PM
  • update to Sp3 without R1
    Thursday, August 29, 2013 3:42 PM
  • Hi Jeff,

    According to the logon statistics, we can figure out that owa is repeatedly proposing log-on requests. This is exactly what causes multiple sessions which are over the registry value of Maximum Allowed Service Sessions.

    The issue mentioned above can be caused by several reasons, such as instable networking or client issue(which is /o=Company/ou=Loc/cn=Recipients/cn=user you mentioned in the first post).  We have to do further troubleshooting by performance monitor, network monitor, trace log and etc. Each of them is time consuming and I would recommend as the best option for the current situation:

    Increase the value of Maximum Allowed Sessions per User.

    As for the low performance we worry about, it seems not that important in our consideration.

    Your understanding is apprecitated.

    Regards,

    Rebecca

    Monday, September 2, 2013 3:31 PM
  • Hi Rebecca,

    Thanks again for your response.

    I opened a case with Microsoft support and they resolved the issue.  They had me change the OWA web.config file on the internet facing CAS server.  The default location is <drive>\Program Files\Microsoft\Exchange Server\<version>\ClientAccess\Owa.  Specifically, we changed the requireSSL to "false" for the httpOnlyCookies="false" requireSSL="true" domain="" parameter.  Then we removed all of the http redirection for the Default Web Site as well as for the AutoDiscover, EWS, OWA, and ECP Virtual directories.

    Once those changes were made then OWA was working again and there were no more 9646 errors either.

    Regards,

    Jeff

    • Marked as answer by jeffmar Tuesday, September 3, 2013 7:59 PM
    Tuesday, September 3, 2013 7:58 PM