All, We are getting frequent errors on Auto accept agent in the last few days. Error says that Event Type: Error Event Source: Auto Accept Agent Event Category: None Event ID: 4097 Date: 6/8/2011 Time: 3:00:29 AM User: N/A Computer: Server1 Description: Exception occurred while processing item "". This item will not be processed. The exception information is: System.NullReferenceException: Object reference not set to an instance of an object. at Microsoft.Exchange.Agents.AutoAccept.ConfigurationManager.get_Item(String key) at Microsoft.Exchange.Agents.AutoAccept.EventSink.UpdateConfiguration(String sMailboxSMTP) at Microsoft.Exchange.Agents.AutoAccept.EventSink.ProcessOnSaveEvent(String itemUrl, DateTime& deliveryTime) at Microsoft.Exchange.Agents.AutoAccept.EventSink.OnSave(IExStoreEventInfo pEventInfo, String bstrURLItem, Int32 lFlags) For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp. At the same time, meeting invites was not getting processed. Did a re-registration for meeting rooms and most of them are working. How ever ,this event is filling the event log every day. Appreciate any assistance on getting a permenant fix. Thanks, ShabaCheers Shaba

See if the below helps. I would think it should as you;re getting System.NullReferenceException: Object reference not set to an instance of an object. http://support.microsoft.com/kb/920861Sukh

Good article given by Sukh. This issue may be caused by: The resource mailboxes are deleted without being un-registered. The system mailbox has stale entries for messages sent to these deleted resource mailboxes. Resolution: 1.Get list of registered mailboxes and save the output in text file. 2.Make auto accept agent service disabled and kill the process from task manager. 3.Un-register all mailboxes using the text file created in stelp1, save the output of this command to a text file. 4.In step 3 you will get list of mailboxes which fail to un-register, search for these mailboxes in Active Directory and confirm they are not present. 5.Follow the KB given by Sukh to delete the stale entries for these mailboxes from system mailboxes. 6.Restart the information store service after all the stale entries are deleted from system mailboxes. 7.Make auto accept agent service manual and start the service. 8.Register again for the mailboxes you needed. Thanks, Evan Liu TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Hi, How about the issue, any updates? Thanks, Evan Liu TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

We identified stale entries which caused the issue on one cluster. By following the KB article - http://support.microsoft.com/kb/920861 , I was able to fix it. But we have few more servers where we couldnt identify any stale meeting rooms registered for auto accept agent - how ever, event log is flooded with 4097. Case opened with MS and working towards the fix. Will let you know. ShabaCheers Shaba