Error in Transform Parse data phase in Native Data Import after the installation of update rollup 11

Unhandled Exception: System.ServiceModel.FaultException`1[[Microsoft.Xrm.Sdk.OrganizationServiceFault, Microsoft.Xrm.Sdk, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]: An unexpected error occurred.Detail:

<OrganizationServiceFault xmlns:i="www.w3.org/.../XMLSchema-instance" xmlns="schemas.microsoft.com/.../Contracts">

 <ErrorCode>-2147220970</ErrorCode>

 <ErrorDetails xmlns:d2p1="schemas.datacontract.org/.../System.Collections.Generic" />

 <Message>An unexpected error occurred.</Message>

 <Timestamp>2013-03-20T16:29:25.1093736Z</Timestamp>

 <InnerFault>

   <ErrorCode>-2147220970</ErrorCode>

   <ErrorDetails xmlns:d3p1="schemas.datacontract.org/.../System.Collections.Generic" />

   <Message>System.MissingMethodException: Microsoft Dynamics CRM has experienced an error. Reference number for administrators or support: #B820CE2D</Message>

   <Timestamp>2013-03-20T16:29:25.1103502Z</Timestamp>

   <InnerFault i:nil="true" />

   <TraceText i:nil="true" />

 </InnerFault>

 <TraceText i:nil="true" />

</OrganizationServiceFault>

  at Microsoft.Crm.Extensibility.OrganizationSdkServiceInternal.Execute(OrganizationRequest request, CorrelationToken correlationToken, CallerOriginToken callerOriginToken, WebServiceType serviceType)

  at Microsoft.Crm.Extensibility.InprocessServiceProxy.ExecuteCore(OrganizationRequest request)

  at Microsoft.Crm.Asynchronous.ImportOperation.RetrieveNotCompletedImportFiles(Guid importId)

  at Microsoft.Crm.Asynchronous.ImportOperation.SetStatusOnLinkedImportFiles(Guid importId, Int32 importStatus)

  at Microsoft.Crm.Asynchronous.ImportOperation.SetImportStatus(Guid importId, Int32 importStatus, Boolean cleanupImportFilesContent)

  at Microsoft.Crm.Asynchronous.ImportOperation.InternalExecute(AsyncEvent asyncEvent)

  at Microsoft.Crm.Asynchronous.AsyncOperationCommand.Execute(AsyncEvent asyncEvent)

  at Microsoft.Crm.Asynchronous.QueueManager.PoolHandler.ProcessAsyncEvent(AsyncEvent asyncEvent)