MSCRMAsync Service Not Working

Hi,

I am Working on CRM 4 to CRM 2011 migration Project. We have restored CRM 4 database in CRM 2011.

After few days MSCRMSync Service suddenly started throwing exceptions and stops on execution of any workflow. I have tried by restarting SQL Server, MSCRMSync Service.. Couldn't help.

Exceptions found in Event Logs are :

1. Host ORGNAME: failed while starting monitoring asynchronous operations queue. Exception: System.TypeLoadException: Could not load type 'Microsoft.Xrm.Sdk.Workflow.ICustomActivityExecutionContext' from assembly 'Microsoft.Xrm.Sdk.Workflow, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'.

      at Microsoft.Crm.Workflow.ActivityHostBase..ctor(ICrmServiceFactory crmServiceFactory, IWorkflowConfiguration configuration, ICrmEventLog eventLog)

      at Microsoft.Crm.Asynchronous.WorkflowHandlerGroup.Start(AsyncService service)

      at Microsoft.Crm.Asynchronous.AsyncService.InitializeComponents()

      at Microsoft.Crm.Asynchronous.AsyncService.StartServiceComponents(Object state)

2. Host ORGNAME: failed while monitoring asynchronous operations queue. Exception: System.TypeLoadException: Could not load type 'Microsoft.Xrm.Sdk.Workflow.ICustomActivityExecutionContext' from assembly 'Microsoft.Xrm.Sdk.Workflow, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'.

      at Microsoft.Crm.Workflow.ActivityHostBase..ctor(ICrmServiceFactory crmServiceFactory, IWorkflowConfiguration configuration, ICrmEventLog eventLog)

      at Microsoft.Crm.Asynchronous.WorkflowHandlerGroup.Start(AsyncService service)

      at Microsoft.Crm.Asynchronous.AsyncService.InitializeComponents()

      at Microsoft.Crm.Asynchronous.AsyncService.StartServiceComponents(Object state)

      at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)

      at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)

      at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()

      at System.Threading.ThreadPoolWorkQueue.Dispatch()

Regards,

Yatin Babaria