I can't get cu8 installed and now my exchange server is behaving very strange I can connect to my outlook 2013 clients but can't receive any email ( internal or external). I checked all service and are running.

I got this error when it errored out.

Error:
The following error was generated when "$error.Clear();
          $fe = get-ActiveSyncVirtualDirectory -server $RoleFqdnOrName -DomainController $RoleDomainController -ErrorAction SilentlyContinue;

          if ($fe -eq $null)
          {
            new-ActiveSyncVirtualDirectory -DomainController $RoleDomainController -Role ClientAccess;
          }
          else
          {
            update-ActiveSyncVirtualDirectory $fe -DomainController $RoleDomainController -InstallIsapiFilter $true
          }
        " was run: "System.Management.Automation.ParameterBindingException: Cannot convert 'System.Object[]' to the type 'Microsoft.Exchange.Configuration.Tasks.VirtualDirectoryIdParameter' required by parameter 'Identity'. Specified method is not supported. ---> System.NotSupportedException: Specified method is not supported.
   at System.Management.Automation.ParameterBinderBase.CoerceTypeAsNeeded(CommandParameterInternal argument, String parameterName, Type toType, ParameterCollectionTypeInformation collectionTypeInfo, Object currentValue)
   --- End of inner exception stack trace ---
   at System.Management.Automation.Internal.PipelineProcessor.SynchronousExecuteEnumerate(Object input, Hashtable errorResults, Boolean enumerate)
   at System.Management.Automation.PipelineOps.InvokePipeline(Object input, Boolean ignoreInput, CommandParameterInternal[][] pipeElements, CommandBaseAst[] pipeElementAsts, CommandRedirection[][] commandRedirections, FunctionContext funcContext)
   at System.Management.Automation.Interpreter.ActionCallInstruction`6.Run(InterpretedFrame frame)
   at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame frame)".

I have two activesync directory on IIS cause we don't want to allow ecp access from outside network.

Hello.
Check the logs for errors, IIS, and work logs of IIS.
Check Configuring ISAPI Filters in IIS 7.

Perhaps reset configuration of the virtual directory. Default settings for Exchange virtual directories
After that, reinstall CU8

thank you for reply but I got it resolved following this link.

http://www.networksteve.com/exchange/topic.php/Cumulative_Update_8_broke_Exchange_2013/?TopicId=45689&Posts=1

thank you all.