Update based on Stefan's pull request.

Author: Heidilohr

articles/virtual-desktop/app-attach.md

@@ -6,7 +6,7 @@ author: Heidilohr
 
 ms.service: virtual-desktop
 ms.topic: conceptual
-ms.date: 12/14/2019
+ms.date: 05/11/2020
 ms.author: helohr
 manager: lizross
 ---
@@ -37,7 +37,7 @@ First, you need to get the OS image you'll use for the MSIX app. To get the OS i
      >[!NOTE]
      >You must be member of the Windows Insider program to access the Windows Insider portal. To learn more about the Windows Insider program, check out our [Windows Insider documentation](/windows-insider/at-home/).
 
-2. Scroll down to the **Select edition** section and select **Windows 10 Insider Preview Enterprise (FAST) – Build 19035** or later.
+2. Scroll down to the **Select edition** section and select **Windows 10 Insider Preview Enterprise (FAST) – Build 19041** or later.
 
 3. Select **Confirm**, then select the language you wish to use, and then select **Confirm** again.
 
@@ -70,6 +70,14 @@ rem Disable Windows Update:
 sc config wuauserv start=disabled
 ```
 
+After you've disabled automatic updates, you must enable Hyper-V because you'll be using the Mound-VHD command to stage and and Dismount-VHD to destage. 
+
+```powershell
+Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V-All
+```
+>[!NOTE]
+>This change will require that you restart the virtual machine.
+
 Next, prepare the VM VHD for Azure and upload the resulting VHD disk to Azure. To learn more, see [Prepare and customize a master VHD image](set-up-customize-master-image.md).
 
 Once you've uploaded the VHD to Azure, create a host pool that's based on this new image by following the instructions in the [Create a host pool by using the Azure Marketplace](create-host-pools-azure-marketplace.md) tutorial.
@@ -253,7 +261,7 @@ Before you update the PowerShell scripts, make sure you have the volume GUID of
 
     {
 
-    Mount-Diskimage -ImagePath $vhdSrc -NoDriveLetter -Access ReadOnly
+    Mount-VHD -Path $vhdSrc -NoDriveLetter -ReadOnly
 
     Write-Host ("Mounting of " + $vhdSrc + " was completed!") -BackgroundColor Green