Hello All,

In the Existing Environment is 2 Mailbox Server and  CAS server Exchange 2013 CU1.

we are facing problem login owa and outlook sometimes. sometimes user can login using owa and outlook and sometimes user cannot login using owa and outlook. i found some error in exchange server IIS. Please see the error and suggest:

Error:

A process serving application pool 'MSExchangeRpcProxyAppPool' suffered a fatal communication error with the Windows Process Activation Service. The process id was '11736'. The data field contains the error number.

A process serving application pool 'MSExchangeServicesAppPool' suffered a fatal communication error with the Windows Process Activation Service. The process id was '6404'. The data field contains the error number.

A process serving application pool 'MSExchangeRpcProxyAppPool' suffered a fatal communication error with the Windows Process Activation Service. The process id was '3896'. The data field contains the error number.

A process serving application pool 'MSExchangeRpcProxyAppPool' suffered a fatal communication error with the Windows Process Activation Service. The process id was '10372'. The data field contains the error number.

Hi Parvez,

What is your CU version? CU1 right, time to upgrade.

Microsoft determined that in most cases this was an issue and have provided a fix in Exchange 2013 CU3.  For most people, this resolves their issue.

However, there is another reason that this could be happening, so if you have applied Exchange 2013 CU3 and you are still hitting this issue, please read on.

Exchange 2013 - The case of the mysterious crashing RPC Proxy Application Pool

Event ID 5011 IIS Application Pool Availability

https://technet.microsoft.com/en-us/library/cc735271(v=ws.10).aspx

Web sites and Web applications depend on the availability of Internet Information Services (IIS) application pools. IIS application pools in turn depend on the Windows Process Activation Service (WAS). If WAS is not running or errors occur during the startup or shutdown of an application pool, Web sites and Web applications may not be available.

Incase you figureout issue is something else and stop the eventlog from filling up.

Suppress WAS Warnings Due to Regular IIS Application Pool Recycling

http://blogs.msdn.com/b/webapps/archive/2014/10/29/suppress-was-warnings-due-to-regular-iis-application-pool-recycling.aspx

Look for clues in the IIS logs in C:\inetpub\logs\LogFiles

Hi,

Is there any other error message coour on Exchange server when those relevant error arise.I find an blog about your question, for your reference: http://blogs.technet.com/b/jamec/archive/2014/01/29/exchange-2013-the-case-of-the-mysterious-crashing-rpc-proxy-application-pool.aspx

Besides, please ensure the Microsoft Exchange RPC Client Access service runing well. Open IIS management and Application Pool, under "Advanced Settings", change "Enable 32 bit Applications" to "Ture" for testing.

If the issue persists, we can use Process Monitor Tool and set it to monitor W3WP.exe to get more details about this issue. Meanwhile, please refer to "Debug Diagnostics tool to troubleshoot an IIS process that stops unexpectedly": https://support.microsoft.com/en-us/kb/919789

Thanks