Product Documentation

Upgrade a XenApp 6.5 worker to a new VDA

Jun 13, 2017

When you run the current product installer on a XenApp 6.5 worker server, it:

  • Removes the server from the XenApp 6.5 farm (this task automatically invokes the XenApp 6.5 installer's command-line interface)
  • Removes the XenApp 6.5 software
  • Installs a new (XenApp 7.6 or later supported release) VDA for Windows Server OS

When you use the installer's graphical interface, you are guided through the same wizard that you used when installing VDAs for Windows Server OS in your new XenApp Site. Similarly, the command-line interface uses the same commands and parameters you use to install other VDAs in your new Site.  

NOTE: Although you can upgrade a XenApp 6.5 worker server, installing the current VDA software on a clean machine provides better security.

You are probably already familiar with using the installer from installing your XenApp core components and other VDAs. Launch the installer on the XenApp 6.5 worker server.

Good to know:

  • This upgrade is valid on XenApp 6.5 servers that are configured in session-host only mode (also called session-only or worker servers).
  • Uninstalling XenApp 6.5 requires several server restarts. When using the command-line interface, you can use the /noreboot option to inhibit that automatic action; however, you must restart the server for the uninstallation and subsequent installation to proceed.
  • If an error occurs during the XenApp uninstallation process, check the uninstall error log referenced in the error message. Uninstall log files reside in the folder "%TEMP%\Citrix\XenDesktop Installation\XenApp 6.5 Uninstall Log Files\."
  • After the upgrade, review IMA-specific settings and registry entries, plus HDX-related system settings and registries. Some settings may no longer apply or might not work in the same way.
  • After you upgrade the XenApp 6.5 worker servers, from Studio in the new XenApp Site, create Machine Catalogs (or edit existing catalogs) for the upgraded workers.
  • If you migrated policy and application settings from a XenApp 6.5 controller server (see Migrate XenApp 6.x), assign the Delivery Groups containing the migrated published applications to the machine catalog that hosted those applications in XenApp 6.5.


Symptoms: Removal of the XenApp 6.5 software fails. The uninstall log contains the message: "Error 25703. An error occurred while plugging XML into Internet Information Server. Setup cannot copy files to your IIS Scripts directory. Please make sure that your IIS installation is correct."
  • Cause: The issue occurs on systems where (1) during the initial XenApp 6.5 installation, you indicated that the Citrix XML Service (CtxHttp.exe) should not share a port with IIS, and (2) .NET Framework 3.5.1 is installed.
  • Resolution:
    1. Remove the Web Server (IIS) role using the Windows Remove Server Roles wizard. (You can reinstall the Web Server (IIS) role later.)
    2. Restart the server.
    3. Using Add/Remove Programs, uninstall the following:
      1. Citrix XenApp 6.5
      2. Microsoft Visual C++ 2005 Redistributable (x64), version 8.0.56336
    4. Restart the server.
    5. Run the XenApp installer to install the VDA for Windows Server OS.