Product Documentation


Apr 14, 2015

You can verify your installation and collect troubleshooting information from your users through the following:

  • Confirm audio and video device detection. On the user device, from the Lync tools menu, choose Tools > Audio Video Settings.
  • Open the Lync About page and confirm connection attributes (status, connection type, and mode). The following screenshot shows the correct connection values.

    If the RealTime Connector is in fallback or non-optimized mode, the value of the Mode field is Un-Optimized. For fallback mode, video and audio processing occurs on the server and the media is sent from the terminal to the server and then back to the terminal.

  • During a call, you can view information about your network health by typing Alt-N. The Network Health window appears, as shown in the following example. Values in red indicate potential problems with the network. To write the values to a text file whose default name is call_statistics_<date>.txt, click Save Statistics.

Find log files

MediaEngineHost.exe writes client-side error logs to %TEMP%\Citrix\RestrictedMediaEngine\ on the local terminal.

The RealTime Connector client application also writes logs to your XenApp or XenDesktop servers. You can find them in the following locations, depending on the client-side operating system.
  • For Windows XP users: C:\Documents and Settings\USERNAME\Local Settings\%Temp%\Citrix\RealTimeConnector\MediaEngine\MediaEngineDebugLogs
  • For Windows 7 users: C:\Users\USERNAME\AppData\Local\Temp\Citrix\RealTimeConnector\MediaEngine\MediaEngineDebugLogs

Determine whether your connection problems are related to DNS issues

If you have DNS problems on the terminal, these can cause the RealTime Connector and the Citrix HDX RealTime Media Engine to fail registration while the Lync application can register successfully. If this occurs, debug and fix the DNS problems from the remote terminal.

Save crash logs for Dell Wyse terminals

On Dell Wyse terminals, the log file of an application crash is not saved when the user works in User mode. To save crash logs, the user must work in Administrator mode. You can find crash logs in MS-RAMDRIVE, which is drive Z by default on Wyse terminals.

Change the location of Citrix HDX RealTime Media Engine error logs

Normally, the error logs from a client application are created on the local, client device. However, such local error logs are sometimes deleted when a terminal user logs off, so a system administrator is unable to retrieve them.

HDX RealTime Media Engine avoids this by writing error messages into the Media Engine error logs on the virtual desktop running on the client device.

To change the write location of Media Engine Host error messages from the virtual desktop back to the local client device

  1. In the registry of the remote desktop running on the client device, in HKEY_CURRENT_USER\Software\Citrix\HDXRTConnectorLC\MediaEngine, create a registry value of type DWORD named EnableRemoteDebugLogging.
  2. Set the EnableRemoteDebugLogging value to 0.

To re-enable remote error message logging on the virtual desktop, set the value of the key to 1 (enabled) or remove the key entirely.

Limit the video frame rate for Citrix HDX RealTime Media Engine

If you are having video problems attributable to a high Frames Per Second (FPS) rate, such as the image breaking up, you can limit the supported FPS with this registry key value: [HKEY_CURRENT_USER\Software\Citrix\HDXRTConnectorLC\MediaEngine] "MaxAllowableFrameRate"="15".

Determine whether your firewall is blocking the RealTime Connector

The RealTime Connector can fail to initialize if a personal firewall blocks the network initialization for too long. This condition resolves itself the next time the program is run after you unblock the application.

When the firewall is blocked, an error message such as the following can appear:

  • RealTime Connector is waiting for the connection from the Media Engine…
  • Failed to maintain RealTime Connector on this device. Communication to the Media Engine was disrupted. Please contact your system administrator.

In such cases, create an exception in the Windows firewall.

Restore Lync to a normal size after starting a second session

Occasionally, when you start a second session on a second terminal while a first session remains open, Microsoft Lync does not open in the second session. It stays minimized in the task bar. To maximize it, right-click the task bar and select Maximize. Then, to restore Lync to a normal size, restart Lync.

Resolve an “Application Not Running” error in the App Center Console

The error Application Not Running can appear when a published application is closed. To resolve this issue, add LyncMonitor.exe to a registry key in the XenApp server. For information, refer to and

Resolve video quality issues when using a wireless network connection

If you experience issues with video quality when using a wireless network connection, try moving closer to the wireless access point. If that does not resolve the issue, try a wired network connection instead. When using a wired network connection, disable the wireless network adapter to avoid transmission issues.

Install a root certificate for the RealTime Media Engine on Windows terminals

Certain Windows terminals do not include a VeriSign root certificate for RealTime Media Engine in the default set of trusted root certificates. If a terminal does not have the required certificate, these issues appear immediately after Lync starts:

  • Lync does not connect to Media Engine.
  • The camera preview does not work.
  • The HDX RealTime Connector program information page does not include an entry for Media Engine.
  • The terminal error log includes the following entry: Media Engine package search failure. It is impossible to launch MediaEngineHost.

For more information about root certificate issues, refer to the following articles:

Obtain a root certificate.

  1. Go to
  2. Under VeriSign Root Package, click Download a root package to download the archive.
  3. Extract files from the archive to the Windows terminal.

Install the root certificate manually or through the Microsoft Management Console (MMC).

  • To perform a manual installation:
    1. From the Windows terminal, navigate to the \roots folder containing the extracted files and then open the folder Verisign Root Certificates > Generation 5 (G5) PCA.
    2. In that folder, right-click VeriSign Class 3 Public Primary Certification Authority - G5.cer and then click Install Certificate.
    3. Scroll below the Security Warning to open the Certificate Import wizard and then click Next.
    4. On the Certificate Store wizard page, click Place all certificates in the following store and then click Browse.
    5. In the Select Certificate Store dialog box, select the Show physical stores check box.
    6. Open the Trusted Root Certification Authorities folder, select Local Computer, and then click OK.
    7. Click Next, review your settings, and then click Finish.
  • To perform the installation with the MMC:
    1. From the Windows terminal, click Start and then type run.
    2. In the Run field, type mmc to open the terminal Console.
    3. In the Console File menu, select Add/Remove Snap-in.
    4. In the Add/Remove Snap-in dialog box, click Add.
    5. Select Certificates and then click Add.
    6. Select Computer Account and then click Next.
    7. Select Local computer and then click Finish.

Resolve installation issues

For software in general, the most common installation problems are related to corrupt system files needed for installation. These errors are rare, but difficult to troubleshoot.

The Media Engine installer requires Microsoft .NET 3.5.1. If it is missing from the computer, install it to resolve the problem. If it is already installed, run a repair installation on .NET.

On some Windows machines, customers encounter errors during software installation when embedded custom-action VB scripts run. Common errors presented to the user or captured in install logs are 2738 and 1720. Some customers have encountered these errors when an anti-virus program places the vbscript.dll ClassID under the HKEY_CURRENT_USER registry hive instead of under HKEY_LOCAL_MACHINE where it is needed for the proper elevated run level.

Run the following registry queries to determine if the vbscript.dll ClassID is installed for the current user, system wide, or both:

  • % reg query HKEY_CURRENT_USER\SOFTWARE\Classes\CLSID{B54F3741-5B07-11CF-A4B0-00AA004A55E8}
  • % reg query HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID{B54F3741-5B07-11CF-A4B0-00AA004A55E8}

The ClassID should appear only for HKEY_LOCAL_MACHINE. If it is under HKEY_CURRENT_USER, follow these steps. If ClassID is under HKEY_LOCAL_MACHINE and not HKEY_CURRENT_USER, start with step 2.

  1. Run an anti-virus clean-up utility:
    1. If the terminal has an anti-virus program installed and the vendor has a clean-up utility, run the clean-up utility.
    2. Re-run the Media Engine installer MSI.
    3. If the issue persists, go to the next step.
  2. Register vbscript.dll:

    The vbscript.dll file or registry reference to its ClassID can become unregistered or corrupted. Follow these steps to register or repair it.

    1. Run CMD.exe as an administrator: Click Start, type cmd, right-click cmd, and click Run as administrator.
    2. Enter in the Command window:
      • For the 32-bit version of Windows: cd %windir%\system32
      • For the 64-bit version of Windows: cd %windir%\syswow64
    3. Enter in the Command window: regsvr32 vbscript.dll
    4. Re-run the Media Engine installer MSI.
    5. If the issue persists, go to the next step.
  3. Remove the vbscript.dll ClassID:
    1. In the Registry Editor, locate and remove registry key HKEY_Current_User\SOFTWARE\Classes\CLSID{ B54F3741-5B07-11CF-A4B0-00AA004A55E8}.
    2. Click Start > Control Panel, navigate to the User Account Control Settings, and then move the slider to Never notify.

      After you complete the troubleshooting, you can revert this change if needed.

    3. Re-run the Media Engine installer MSI.
    4. If the issue persists, go to the next step.
  4. Repair corrupt system files with System File Checker:
    1. Run CMD.exe as an administrator: Click Start, type cmd, right-click cmd, and click Run as administrator.
    2. In the Command window, enter: sfc /scannow
    3. Re-run the Media Engine installer MSI.
    4. If the issue persists, go to the next step.
  5. Restore corrupt registry entries to their original state:
    1. Restart the Windows terminal and during the restart, insert the OS installation DVD to boot from it.

      The OS installation DVD must match the Windows service pack installed on the terminal.

    2. Follow the installation steps, selecting the option to repair the OS.
    3. Re-run the Media Engine installer MSI.