During installation of Citrix XenDesktop, you may come across the below scenario where installer says many of the core XenDesktop components: “This component cannot be installed on this machine” as shown below
Possible causes:
This usually happens if the system that you chosen already running some version of the same components or as part of other application running the same components (for example it may be already running Web Interface role for XenApp). This most possibly happens on systems that running XenApp.
Fixes:
In my case I ended up uninstalling XenApp 6.5 from my test server and then I was given options to install XenDesktop. XenDesktop installer works even if you all other XenApp components installed on the server
Conclusion: You can NOT install XenDesktop on XenApp server.