Event generated on server & post this event database crash and failover.

Log Name:      Application
Source:        MSExchangeIS
Date:          01.06.2015 12:56:27
Event ID:      1002
Task Category: General
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      <hostname>
Description:
Unhandled exception (System.ArgumentException: Parameter "legacyExchangeDN" must be non-empty string.
Parameter name: legacyExchangeDN
   at Microsoft.Exchange.Data.Directory.Recipient.ADRecipientObjectSession.FindByLegacyExchangeDN(String legacyExchangeDN)
   at Microsoft.Exchange.Server.Storage.DirectoryServices.ADObjectWrappers.ADRecipientSession.FindByLegacyExchangeDN(IExecutionContext context, String legacyExchangeDN)
   at Microsoft.Exchange.Server.Storage.DirectoryServices.Directory.LoadAddressInfoByLegacyDn(IExecutionContext context, TenantHint tenantHint, String legacyDN, Boolean loadPublicDelegates)
   at Microsoft.Exchange.Server.Storage.DirectoryServices.Directory.GetAddressInfoImpl(IExecutionContext context, TenantHint tenantHint, String legacyDN, Boolean loadPublicDelegates)
   at Microsoft.Exchange.Server.Storage.MapiDisp.RopHandler.TransportSend(MapiContext context, MapiMessage message, TransportSendResultFactory resultFactory)
   at Microsoft.Exchange.Server.Storage.MapiDisp.RopHandlerBase.TransportSend(IServerObject serverObject, TransportSendResultFactory resultFactory)
   at Microsoft.Exchange.RpcClientAccess.Parser.RopTransportSend.InternalExecute(IServerObject serverObject, IRopHandler ropHandler, ArraySegment`1 outputBuffer)
   at Microsoft.Exchange.RpcClientAccess.Parser.InputRop.Execute(IConnectionInformation connection, IRopDriver ropDriver, ServerObjectHandleTable handleTable, ArraySegment`1 outputBuffer)
   at Microsoft.Exchange.RpcClientAccess.Parser.RopDriver.ExecuteRops(List`1 inputArraySegmentList, ServerObjectHandleTable serverObjectHandleTable, ArraySegment`1 outputBuffer, Int32 outputIndex, Int32 maxOutputSize, Boolean isOutputBufferMaxSize, Int32& outputSize, AuxiliaryData auxiliaryData, Boolean isFake, Byte[]& fakeOut)
   at Microsoft.Exchange.RpcClientAccess.Parser.RopDriver.Execute(IList`1 inputBufferArray, ArraySegment`1 outputBuffer, Int32& outputSize, AuxiliaryData auxiliaryData, Boolean isFake, Byte[]& fakeOut)
   at Microsoft.Exchange.Server.Storage.MapiDisp.MapiRpc.<>c__DisplayClass9.<DoRpc>b__6(MapiContext operationContext, MapiSession& session, Boolean& deregisterSession, AuxiliaryData auxiliaryData)
   at Microsoft.Exchange.Server.Storage.MapiDisp.MapiRpc.Execute(IExecutionDiagnostics executionDiagnostics, MapiContext outerContext, String functionName, Boolean isRpc, IntPtr& contextHandle, Boolean tryLockSession, String userDn, IList`1 dataIn, Int32 sizeInMegabytes, ArraySegment`1 auxIn, ArraySegment`1 auxOut, Int32& sizeAuxOut, ExecuteDelegate executeDelegate)
   at Microsoft.Exchange.Server.Storage.MapiDisp.MapiRpc.DoRpc(IExecutionDiagnostics executionDiagnostics, IntPtr& contextHandle, IList`1 ropInArraySegments, ArraySegment`1 ropOut, Int32& sizeRopOut, Boolean internalAccessPrivileges, ArraySegment`1 auxIn, ArraySegment`1 auxOut, Int32& sizeAuxOut, Boolean fakeRequest, Byte[]& fakeOut)
   at Microsoft.Exchange.Server.Storage.MapiDisp.PoolRpcServer.EcDoRpc(MapiExecutionDiagnostics executionDiagnostics, IntPtr& sessionHandle, UInt32 flags, UInt32 maximumResponseSize, ArraySegment`1 request, ArraySegment`1 auxiliaryIn, IPoolSessionDoRpcCompletion completion)
   at Microsoft.Exchange.Server.Storage.MapiDisp.PoolRpcServer.EcPoolSessionDoRpc_Unwrapped(MapiExecutionDiagnostics executionDiagnostics, IntPtr contextHandle, UInt32 sessionHandle, UInt32 flags, UInt32 maximumResponseSize, ArraySegment`1 request, ArraySegment`1 auxiliaryIn, IPoolSessionDoRpcCompletion completion)
   at Microsoft.Exchange.Server.Storage.MapiDisp.PoolRpcServer.<>c__DisplayClassf.<EcPoolSessionDoRpc>b__c()
   at Microsoft.Exchange.Common.IL.ILUtil.DoTryFilterCatch[T](TryDelegate tryDelegate, GenericFilterDelegate filterDelegate, GenericCatchDelegate catchDelegate, T state)).

Hi,

Beginning with Exchange 2000, the Exchange configuration is stored in the Active Directory database and there is no obj-Dist-Name. Exchange 200x uses the LegacyExchangeDN for every "Exchange activated" (mail-enabled users, public folders, and Exchange system configuration objects) object. The Exchange Recipient Update Service (RUS) is responsible for filling the LegacyExchangeDN attribute. Normal Active Directory objects which aren't e-mail activated have a LegayExchangeDN but have no value.

Basis on the Event ID 1002 with Source MSExchangeIS, it indicate that some objects LegacyExchangeDN is no set.
Please run below command to double check: Get-Mailbox | Where {$_.LegacyExchangeDN eq } | FL Identity,*Legacy*

Meanwhile, please try to restart Exchange Information store service or Exchange server for test.

Thanks

Thanks Allen for information,

Adding to above query post event 1002 we received with below error event & we found that mentioned mailbox guid user is not exist in exchange but after that database failover.

 
Log Name:      Application

Source:        MSExchangeIS

Date:          01.06.2015 12:56:27

Event ID:      1013

Task Category: General

Level:         Error

Keywords:      Classic

User:          N/A

Computer:      <hostname>
Description:

The mailbox with mailboxguid "userguid" caused crash or resource outage on database (GUID="Databaseguid"). Description: ArgumentException: MEDDR.ADRecipientObjectSession.FindByLegacyExchangeDN,MESSDSADOW.ADRecipientSession.FindByLegacyExchangeDN,MESSDS.Directory.LoadAddressInfoByLegacyDn,MESSDS.Directory.GetAddressInfoImpl,MESSMD.RopHandler.TransportSend,MESSMD.RopHandlerBase.TransportSend,ME.