OWA, Something went wrong :( and the case of the missing sharedwebconfig.config

Good morning.  I wanted to take the time this morning to go over an issue I saw the other day.  This issue was pretty difficult to track down, so I figured I would go over as many of the symptoms as possible.  This is in hope that someone suffering this issue will have an easier time of it.

So I am working with a deployment consultant and he has an issue where OWA (Outlook Web Access) is not working.  We have a new deployment of three 2016 Exchange servers. First thing, I checked the version of .NET, as my group have seen a few cases of .NET 4.6.1 on Exchange.  Well it appears that WSUS had pushed it.  I figured we had found the issue.  We reverted .NET to 4.5.2 and tested on one server.  OWA is now working.  So I was thinking great, we have the issue resolved.  Unfortunately, after reverting all 3 servers there are still problems.  It appears that one of them is working, but two are not.  Here are the symptoms I found.

• In the IIS logs for the Exchange frontend are the following lines:

  timestamp::1 POST /owa/auth.owa &CorrelationID=<empty>;&ClientId=123&cafeReqId=123;&encoding=; 443 user.name ::1 Mozilla/5.0+(Windows+NT+6.3;+WOW64;+Trident/7.0;+rv:11.0)+like+Gecko https://localhost/owa/auth/logon.aspx?replaceCurrent=1&url=https%3a%2f%2flocalhost%2fowa%2f%23authRedirect%3dtrue 302 0 0 0
  timestamp::1 POST /owa/sessiondata.ashx appcacheclient=1&acver=15.1.225.42&crr=1&CorrelationID=123;&ClientId=123&ClientRequestId=123&encoding=;&cafeReqId=123; 443 user.name ::1 Mozilla/5.0+(Windows+NT+6.3;+WOW64;+Trident/7.0;+rv:11.0)+like+Gecko - 302 0 0 15
  timestamp::1 GET /owa/auth/errorFE.aspx httpCode=500&CorrelationID=123;&ClientId=123&cafeReqId=123;&encoding=; 443 - ::1 Mozilla/5.0+(Windows+NT+6.3;+WOW64;+Trident/7.0;+rv:11.0)+like+Gecko - 200 0 0 703
  timestamp::1 POST /owa/plt1.ashx cId=123&msg=USRCompositeServerErr&tg=&MDB=789&nId=0000000000000000&MBX=123&sdCoId=123_123&sds=200&fe=FrontEndSERVERNAME&be=null&cbe=null&cver=15.1.225.42&sdver=null&...+like+Gecko - 302 0 64 15
  timestamp::1 GET /owa/auth/errorFE.aspx httpCode=500&CorrelationID=<empty>;&ClientId=123&cafeReqId=123;&encoding=; 443 - ::1 Mozilla/5.0+(Windows+NT+6.3;+WOW64;+Trident/7.0;+rv:11.0)+like+Gecko - 200 0 0 0
  timestamp::1 GET /owa/ bO=1&CorrelationID=<empty>;&ClientId=123&ClientRequestId=123&encoding=;&cafeReqId=123; 443 user.name ::1 Mozilla/5.0+(Windows+NT+6.3;+WOW64;+Trident/7.0;+rv:11.0)+like+Gecko - 302 0 0 0
  timestamp::1 GET /owa/auth/errorFE.aspx httpCode=500&CorrelationID=<empty>;&ClientId=123&cafeReqId=123;&encoding=; 443 - ::1 Mozilla/5.0+(Windows+NT+6.3;+WOW64;+Trident/7.0;+rv:11.0)+like+Gecko - 200 0 0 15

• In the IIS logs for the Exchange backend, the following is found:

  timestamp ::1 GET /owa/auth/15.1.225/themes/resources/segoeui-regular.eot &CorrelationID=<empty>;&ClientId=123&cafeReqId=123;&encoding=; 443 - ::1 Mozilla/5.0+(Windows+NT+6.3;+WOW64;+Trident/7.0;+rv:11.0)+like+Gecko https://localhost/owa/auth/errorFE.aspx?httpCode=500 200 0 0 0
  timestamp ::1 GET /owa/auth/15.1.225/themes/resources/segoeui-semilight.eot &CorrelationID=<empty>;&ClientId=123&cafeReqId=123;&encoding=; 443 - ::1 Mozilla/5.0+(Windows+NT+6.3;+WOW64;+Trident/7.0;+rv:11.0)+like+Gecko https://localhost/owa/auth/errorFE.aspx?httpCode=500 200 0 0 0

• Checking the event log gives an event ID 1309 every time OWA is accessed.  Below are the details.

  Log Name:      Application
  Source:        ASP.NET 4.0.30319.0
  Date:          3/19/2016 5:49:48 AM
  Event ID:      1309
  Task Category: Web Event
  Level:         Warning
  Keywords:      Classic
  User:          N/A
  Computer:      Exchange2016.MyExchange.com
  Description:
  Event code: 3005 
  Event message: An unhandled exception has occurred. 
  Event time: date/time 
  Event time (UTC): date/time 
  Event ID: ...
  ...
  
  ...
  ...
  
  <Data>Exception has been thrown by the target of an invocation.
     ...
  ...
  ...
  ...
     at System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext)
  
  Could not load file or assembly 'Microsoft.Exchange.Diagnostics, Version=15.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.
     at Microsoft.Exchange.Clients.Owa2.Server.Core.OwaApplication..ctor()
     at Microsoft.Exchange.Clients.Owa2.Server.Core.BaseApplication.CreateInstance()
     at ASP.global_asax..ctor()
  
  </Data>
  ...
  ...

After some extensive checking of the modules in IIS (Internet Information Services), there did not appear to be a configuration issue.  I then tripped upon the following blog article.  This led me to a Microsoft KB on the topic.  It turns out that sometimes when you install Exchange, the SharedWebConfig.config file does not get created.  The fix is to copy one from a working server.  Well what if you don’t have a working server?  In this case we did, but what if you just have one server?  You are in luck.  Here is a copy of the SharedWebConfig.config file.  Just rename the extension from .doc to .config.  I took this from an RTM Exchange 2016 server, so I am not sure it will work in 2013.

I hope this helps you out.