Category Archives: Uncategorized

Why Citrix and Microsoft’s new servicing models now make sense

OK, so I wasted a little bit of time. I know.. it’s a shame when that happens, but it’s even worse to make the same mistake twice! So please read on in case you head down the same road without keeping your eyes peeled for the pitfalls. So what’s the take home message of this post? Microsoft and Citrix now need us (no actually, require us) to do as every professional should always do, and plan our release schedules properly!

This post discusses an issue I experienced installing Citrix XenDesktop VDA 7.15 on Windows 10 Fall Creator’s Update – receiving error 1603 when the Citrix Diagnostic Facility component failed to install. If you’re short on time, skip to the end for a series of helpful links – otherwise, bear with me and I’ll take you on a short journey to grudging mindset shift!

I’d wasted a morning patching a Citrix base image from Windows 10 build 1703 to 1709 Creator’s Fall update because we were looking to create a clean desktop for some developers to test their software releases on. But try as I might, the Citrix 7.15 VDA installer wouldn’t complete and always terminated with error 1603 –  the Citrix Diagnostic Facility (CDF) service had failed to install. After investigating the logs though it wasn’t clear why, other than a permissions failure on C:\Windows\assembly\tmp – and even checking those showed little evidence for the cause of the problem.

But here goes, after a little bit more digging I discovered that the latest Citrix VDA does NOT support the latest semi-annual ‘targeted’ release of Windows 10 (1709). See issue #1 on Citrix blog post.

Could I believe it? No, not at first really – how could a desktop OS release made generally available on 17th October 2017 not be compatible with the latest Citrix VDA which has also been chosen recently as the most recent Long Term Service Release version? Surely this new XenDesktop LTSR release would have been coordinated with Microsoft’s own release schedule, with release candidates being shared well in advance so that both vendor’s would have had a chance to test their interaction together?

Apparently not – and therein lies the message. You cannot expect that each vendor is attempting to align their minor and major servicing schedules with each other! ..Assuming.. that the latest Citrix VDA will work with the latest release of Windows is no longer going to float, and that’s why we all need to fully commit to the “test, test and test again” approach.

In fact, the logic was established a long time ago.  The last LTSR release of XenDesktop (7.6) did not support Windows 10 claiming this as a ‘notable exclusion’ despite the fact that early Windows 10 versions had been around for some time.

Notable Exclusions: These are components or features that are just not well suited for the extended lifecycle typically because this is newer technology that we plan on making significant enhancements to over time.  This is where Windows 10 fell when we originally launched 7.6 LTSR.

Citrix then later added retrospective support for Windows 10 by encouraging the use of VDA 7.9 in conjunction with the XenDesktop 7.6 LTSR release when it appeared that this combination worked well. However hope for the future compatibility was even made clear at this time with the following statement being added to the end of that post.

Finally, we want to note that Citrix is targeting to announce a new LTSR version in 2017 adding full LTSR benefits for the Windows 10 platform. However, this current announcement makes it easier for you to jump on Windows 10 desktop virtualization today while still maintaining all the benefits of being LTSR compliant.

And whilst it is indeed true that XenDesktop 7.15 LTSR release fully supports Windows 10 current branch/semi annual channel, it seems that only a simple statement on ‘requiring VDA 7.9 or later’ was made as long as you are happy to stick to the ‘Current release’ path:

Note about Windows 10: Regular support for Windows 10 is available through the Current Release path. Windows 10 does not get the full set of 7.15 LTSR benefits. For deployments that include Windows 10 machines, Citrix recommends that you use the Current Release Version 7.9 or later of the VDA for Desktop OS and of Provisioning Services.

A separate article entitled Windows 10 Compatibility with Citrix XenDesktop makes this clearer,

  • VDA: Although Semi-Annual Channel Targeted releases are intended for pilot trials, Citrix will provide limited support (configuration only) for VDA installations on Windows 10 Semi-Annual Channel Targeted releases, starting from version 1709 forward.

..and goes on further to say that ‘targeted’ releases such as Windows 10 Fall Creator’s Update are not guaranteed to be compatible:

While the Desktop OS VDA is expected to install and work on Windows 10 Semi-Annual Channel Targeted versions, Citrix does not guarantee proper functionality with these builds.

So there – it’s now clear. The LTSR releases, even the most recent, were never intended to deliver the latest compatibility with Microsoft’s own servicing schedule. It just happens in this case that VDA 7.15 is the most recent VDA available currently and for some reason Citrix also chose to adopt this as the version included in the latest LTSR release.

If you’re intending to use LTSR versions and maintain full compatibility with Windows 10 it seems that the only sensible way forward is to fall back on the most recent Semi-Annual Channel release (build 1703) and wait for the next LTSR cumulative release that adds support for the previously circulated Win10 ‘targeted’ version after all of the wrinkles have been ironed out. This is very well explained at the end of the linked article above, which simply states that you can’t be sure of support for specific Windows 10 versions unless you match them with the approved VDA for that Semi-annual channel release. Anything newer just might not work.

  • Windows 10 Creator’s Update (Version 1703) – use VDA 7.9/7.15 for LTSR support
  • Windows 10 Fall Creator’s Update (Version 1709) – Not supported!

So what’s the moral of the story, after all? Citrix and Microsoft have taken the stance to deliver frequent releases for those who are happy to trail-blaze and hotfix, depending upon their current release and semi-annual targeted releases respectively. But if you want to rely upon well-tested and proven operating system and VDA platforms – which are likely to survive the test of time (without high levels of maintenance and unpredictable results) then stick to the aligned Citrix LTSR and Windows Semi-Annual channel versions and plan your releases several months in advance. Anything else, and you could be left scratching your head for a short while until the penny drops!

Update: Since writing this post I’ve become aware of a clear summary of the current situation documented within Carl Stalhood’s excellent VDA 7.15 installation notes under point #7. Citrix have stated that they plan to provide retrospective support for VDA 7.15 on Windows 10 Version 1709 under two scenarios:

  • A new patch (now released) on Nov 14th 2017 (KB4051314) will provide the ability to update an existing Windows installation and existing VDA to Windows 10 version 1709
  • A new patch to be released via the Microsoft Update Catalogue in November Week 4 will allow you to do a fresh new VDA install on a clean Windows 10 version 1709.

NB This is a first draft of this post with minor edits. If you believe that anything included here is erroneous or misleading please get in contact/drop me a line so that I can clean it up. Thanks for reading!

Useful references:

Windows 10 Compatibility with Citrix XenDesktop

Windows 10 Fall Creators Update (v1709) – Citrix Known Issues

Windows 10 Creators Update (v1703) – Citrix Known Issues

XenApp and XenDesktop 7.15 LTSR

Adding Windows 10 Compatibility to XenApp and XenDesktop 7.6 LTSR

FAQ: XenApp, XenDesktop, and XenServer Servicing Options (LTSR)

Windows 10 update history

Windows as a service: Simplified and Aligned

How to get the Windows 10 Fall Creators Update



LS telcom AG launches TV white space database

As of 01/10/2014, LS telcom AG is now fully approved by the FCC for operation as a TV white space database administrator.

Also detailed in a post here, alongside other approved administrators, the system’s launch was confirmed following testing coordinated between several parties.

The system is available for use by anyone requiring access to radio spectrum located within unused TV channels for use by certain unlicensed devices and protected devices such as wireless microphones.

The new TV white space database can be accessed at

Deleting cached Outlook records in the To: line

We came across a strange problem today whenever a user tried to email one of their contacts, Outlook displayed a message saying that ‘the Operation Failed’. This seemed strange as they could send email to all their other email addresses and contacts. Strangely we were able to send email when the default mail format option was changed to Plain Text, however the only permanent solution that worked was to delete the Outlook name cache. I found this snippet useful:

To remove an email address from the list that has already been cached, to prevent it from being suggested again, open a new message and begin typing in the email address. Select the email address to be removed by using the up and down arrow keys. Once the email address to be removed is highlighted, hit the Delete key. If you would prefer to remove all cached email addresses, then the .nk2 file can be deleted, which is where Outlook stores them. The file is normally located in C:\Documents and Settings\[USERNAME]\Application Data\Microsoft\Outlook.