We just put in Exchange 2013 and are seeing HTTP 500 errors when trying to log on to a 2010 mailbox through OWA. I've tried resetting all virtual directories and different combinations of authentication to no avail. The error that we see when tracing in IIS is:

<fieldset class="no-border" id="section_detail_96">96. -GENERAL_SET_RESPONSE_HEADER

HeaderName	X-CasErrorCode
HeaderValue	ServerNotFound
Replace	true

</fieldset><fieldset class="no-border" id="section_detail_97"> 0 ms Informational 97. -GENERAL_SET_RESPONSE_HEADER

HeaderName	Cache-Control
HeaderValue	private
Replace	true

</fieldset><fieldset class="no-border" id="section_detail_98"> 0 ms Informational 98. -GENERAL_SET_RESPONSE_HEADER

HeaderName	X-AspNet-Version
HeaderValue	4.0.30319
Replace	true

</fieldset><fieldset class="no-border" id="section_detail_99"> 0 ms Informational 99. -AspNetHttpHandlerLeave

ConnID	0
Context ID	{80000141-0000-FF00-B63F-84710C7967BB}

</fieldset><fieldset class="no-border" id="section_detail_100"> 0 ms Warning 100. -MODULE_SET_RESPONSE_ERROR_STATUS

ModuleName	ManagedPipelineHandler
Notification	EXECUTE_REQUEST_HANDLER
HttpStatus	500
HttpReason	Internal Server Error
HttpSubStatus	0
ErrorCode	The operation completed successfully. (0x0)
ConfigExceptionInfo

</fieldset>

I can only find one forum post about this and it's not answered, so we've come up stumped.

Hi Benorb,

Please check if you have followed all the steps outlined in this wizard:

Microsoft Exchange Server Deployment Assistant:

https://technet.microsoft.com/en-us/office/dn756393.aspx?f=255&MSPPError=-2147217396

Make sure you are not pointing the external or internal loadbalanced url to Exchange 2010.

All URLs should be pointing towards Ex2013 IPs only. Ex2013 will proxy the requests based on the mailbox location.

try https:\\Ex2010hostname.domain.com\owa

Read this to understand more on it

http://blogs.technet.com/b/exchange/archive/2014/03/12/client-connectivity-in-an-exchange-2013-coexistence-environment.as

Hello,

Thanks for the information. I have read through that blog and I've configured everything according to the deployment assistant, yet we still see this error.

Our OWA/ECP virtual directories are configured as directed and yet we still see this happening. Accessing directly on 2010 works fine.

Thanks,

Ben

Hi benorb,

Thank you for your question.

By default, if the Exchange 2013 and Exchange 2010 are co-existed in the same organization, the Exchange 2013 will proxy the request to Exchange 2010 automatically for internal user and external user. So we suggest you change the virtual directory to the default setting, then restart IIS to check if the issue persist. We could refer to the following link to change the setting into default setting:

https://technet.microsoft.com/en-us/library/gg247612(v=exchg.150).aspx

We could refer to the following link to learn about proxy and redirect:

https://technet.microsoft.com/en-us/library/bb310763(v=exchg.141).aspx

If there are any questions regarding this issue, please be free to let me know.

Best Regard,

Jim

Hi Benorb,

To put your issue correctly.

You have a Exchange 2010 mailbox. OWA url pointing towards Ex2013, when used to login, you get errors.

But if you use Ex2010 direct Url or Ex2013 mailbox with Ex2013 url it works fine.

This would mean there is an issue with Ex2013, Ex2010 proxying. Mostly two things involved, the URL declaration is misconfigured somewhere or Ex2013 is not able to reach the Ex2010.domain.com using the direct url.

Refer to this guide and check if works for you.

Issues with Exchange 2013 and Exchange 2010 Coexistence:

http://www.techtalklive.org/ttlblog/Pages/Exchange-2010-2013-Coexistence.aspx

Ambigous URLs prevent Exchange 2013 proxy to 2010:

https://shanejacksonitpro.wordpress.com/2015/03/19/new-blog-post-ambigous-urls-prevent-exchange-2013-proxy-to-2010-msexchange-office365/

Ambiguous URLs and their effect on Exchange 2010 to Exchange 2013 Migrations:

http://blogs.technet.com/b/exchange/archive/2013/05/23/ambiguous-urls-and-their-effect-on-exchange-2010-to-exchange-2013-migrations.aspx

Hello,

Thanks for the replies thus far. Looking at the HTTP_Proxy logs on the 2013 server that is trying to send a user to Exchange 2010 OWA we see the following logs:

2015-08-17T09:58:21.341Z,bc5cf38a-3b28-41ee-92ba-8b9e99046edd,15,0,1104,2,,Owa,localhost,/owa/auth.owa,,FBA,true,LONDON\autestmbx,,Sid~S-1-5-21-1801674531-1957994488-1708537768-13776,Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; Touch; rv:11.0) like Gecko,::1,CA1-PRO-EX01,500,,ServerNotFound,POST,,,,,WindowsIdentity,,AU1-PRO-EXC01,2139,160,,,,35,2225,,0,3;,3,5;3;3;,11,14,,0,2261,0,,,,,,,,,0,2225,1,,2226,,2261,2261,,,,BeginRequest=2015-08-17T09:58:19.075Z;CorrelationID=<empty>;ProxyState-Run=None;ServerLocatorCall=DM:17fd46d7-84fc-450d-808e-58cef54c3206~~orbis.co.uk;DownLevelTargetHash=0/-1/1;ProxyState-Complete=CalculateBackEnd;EndRequest=2015-08-17T09:58:21.325Z;I32:ATE.C[CA1-PRO-DC02.orbisfunds.ca]=8;F:ATE.AL[CA1-PRO-DC02.orbisfunds.ca]=0;I32:ATE.C[CA1-PRO-DC01.orbisfunds.ca]=1;F:ATE.AL[CA1-PRO-DC01.orbisfunds.ca]=0;I32:ADS.C[CA1-PRO-DC01]=1;F:ADS.AL[CA1-PRO-DC01]=2.1023;I32:ADS.C[CA1-PRO-DC02]=5;F:ADS.AL[CA1-PRO-DC02]=5.07908;I32:ADR.C[CA1-PRO-DC02]=3;F:ADR.AL[CA1-PRO-DC02]=3.059233,HttpProxyException=Microsoft.Exchange.HttpProxy.HttpProxyException: Unable to find proper back end service for Sid~S-1-5-21-1801674531-1957994488-1708537768-13776 in site CN Sydney CN Sites CN Configuration DC orbis DC co DC uk. ---> Microsoft.Exchange.HttpProxy.NoAvailableDownLevelBackEndException: Unable to find proper back end service for Sid~S-1-5-21-1801674531-1957994488-1708537768-13776 in site CN Sydney CN Sites CN Configuration DC orbis DC co DC uk.    at Microsoft.Exchange.HttpProxy.DownLevelServerManager.GetClientAccessServiceFromList[ServiceType](List`1 serverList  ServiceTopology topology  AnchorMailbox anchorMailbox  Site targetSite  ClientAccessType clientAccessType  Predicate`1 otherFilter  RequestDetailsLogger logger)    at Microsoft.Exchange.HttpProxy.DownLevelServerManager.GetClientAccessServiceInSite[ServiceType](ServiceTopology topology  AnchorMailbox anchorMailbox  Site targetSite  ClientAccessType clientAccessType  Predicate`1 otherFilter  RequestDetailsLogger logger)    at Microsoft.Exchange.HttpProxy.DownLevelServerManager.GetDownLevelClientAccessServer[ServiceType](AnchorMailbox anchorMailbox  BackEndServer mailboxServer  ClientAccessType clientAccessType  RequestDetailsLogger logger  Boolean calculateRedirectUrl  Uri& redirectUrl)    at Microsoft.Exchange.HttpProxy.FbaFormPostProxyRequestHandler.GetDownLevelClientAccessServer(AnchorMailbox anchorMailbox  BackEndServer mailboxServer)    at Microsoft.Exchange.HttpProxy.LatencyTracker.GetLatency[T](Func`1 operationToTrack  Int64& latency)    at Microsoft.Exchange.HttpProxy.ProxyRequestHandler.InternalOnCalculateTargetBackEndCompleted(TargetCalculationCallbackBeacon beacon)    at Microsoft.Exchange.HttpProxy.ProxyRequestHandler.<>c__DisplayClass3f.<OnCalculateTargetBackEndCompleted>b__3e()    --- End of inner exception stack trace ---;

Judging by this it's unable to create the URL to send the user to: Microsoft.Exchange.HttpProxy.NoAvailableDownLevelBackEndException: Unable to find proper back end service for