Hi CAS server : Exchange 2010 on Windows 2008 R2 64bit I am having OWA connection issue, try to browse the owa page in CAS server error : Request Url: https://127.0.0.1:443/owa/ User host address: 127.0.0.1 OWA version: 14.1.270.1 Exception Exception type: System.NullReferenceException Exception message: Object reference not set to an instance of an object. Call stack Microsoft.Exchange.Clients.Owa.Core.RequestDispatcher.GetUserIdentities(OwaContext owaContext, OwaIdentity& logonIdentity, OwaIdentity& mailboxIdentity, Boolean& isExplicitLogon, Boolean& isAlternateMailbox, ExchangePrincipal& logonExchangePrincipal) Microsoft.Exchange.Clients.Owa.Core.RequestDispatcher.InternalDispatchRequest(OwaContext owaContext) Microsoft.Exchange.Clients.Owa.Core.RequestDispatcher.DispatchRequest(OwaContext owaContext) Microsoft.Exchange.Clients.Owa.Core.OwaRequestEventInspector.OnPostAuthorizeRequest(Object sender, EventArgs e) System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) Event log : Log Name: Application Source: Microsoft-Windows-IIS-W3SVC-WP Date: 4/7/2011 10:11:55 AM Event ID: 2280 Task Category: None Level: Error Keywords: Classic User: N/A Computer: MEXCHCAS01.mediacorp.grp Description: The Module DLL C:\Program Files\Microsoft\Exchange Server\V14\ClientAccess\Owa\auth\exppw.dll failed to load. The data is the error. Event Xml: <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event"> <System> <Provider Name="Microsoft-Windows-IIS-W3SVC-WP" Guid="{670080D9-742A-4187-8D16-41143D1290BD}" EventSourceName="W3SVC-WP" /> <EventID Qualifiers="49152">2280</EventID> <Version>0</Version> <Level>2</Level> <Task>0</Task> <Opcode>0</Opcode> <Keywords>0x80000000000000</Keywords> <TimeCreated SystemTime="2011-04-07T02:11:55.000000000Z" /> <EventRecordID>99632</EventRecordID> <Correlation /> <Execution ProcessID="0" ThreadID="0" /> <Channel>Application</Channel> <Computer>MEXCHCAS01.mediacorp.grp</Computer> <Security /> </System> <EventData> <Data Name="ModuleDll">C:\Program Files\Microsoft\Exchange Server\V14\ClientAccess\Owa\auth\exppw.dll</Data> <Binary>05000000</Binary> </EventData> </Event> Have tried to restart the IIS services and server, but problem persist. Wondering if anyone can advice? thanks and regards Jinfa

This is a fairly generic error. Is your public folders working ok? If you open adsiedit and navigate to the public folder store, is it inheriting permissions? Can you run exchange best practice analyzer and post the report?James Chong MCITP | EA | EMA; MCSE | M+, S+ Security+, Project+, ITIL msexchangetips.blogspot.com

Hi JInfa, In IIS 7.0, worker processes are managed by WAS (the Windows Process Activation Service). If a worker process fails to respond, you may get this error. Please Verify that an application pool worker process is running in CAS server and veiry this. See below KB/s for event id 2280. Also run EXBPA as suggested by James above and share information with us. Event ID 2280 — IIS Worker Process Availability:: http://technet.microsoft.com/en-us/library/cc735182(WS.10).aspx Anil