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FAQ's Lync/SfB

Frequently Asked Questions for Lync/SfB

I have Microsoft Office installed but Busylight won’t start?

Please note: Busylight won't start if there no compatible Microsoft Lync or Skype for Business client installed.

Microsoft Lync 2010/2013 and Skype for Business 2015 - Two common causes of errors

If a user is experiencing issues with Busylight (i.e. Busylight does not light up), please ensure the user:

  1. does not have both Lync 2010 AND Lync 2013 clients installed on the same PC.
  2. is not running an outdated version of Lync 2010/2013 (see list of updates for Lync 2010 and Lync 2013).
Skype for Business 2016 – One common error

If Busylight does not start or function correctly after Office was installed or updated (and some cases removed), it’s typically because some registry values got messed up - in particular when upgrading to Office 2016/Office365 x64. Please keep this in mind when choosing x32 over x64 of Office.

Running a repair on your Microsoft Office will typically fix the broken registry entries:

  • Go to Control panel > Programs and features > Rightclick your Microsoft Office product > Select repair > Choose Online Repair if asked and follow the guide.


I get an error when trying to start Busylight for Lync or Skype for Business?

Busylight UC for Lync/SfB requires .Net framework 3.5. On some Win8 and Win8.1 machines .NET 3.5 has been deactivated. Please see this guide on how to enable it:

If you are sure you have .Net 3.5 installed, please confirm that the installed version matches the bit-version of your Windows.

When you know you are running the correct version of .Net 3.5 but still having problems, please try a repair of .Net 3.5.


I experience COM errors?

The Busylight Software is using the Microsoft Lync SDK to connect to the running instance of the Microsoft Skype for Business client (aka Lync client). 

The LyncSDK uses the Windows Component Object Model (COM) infrastructure, which hides the different Client versions and 32/64 bit instances.
(see for details)

The COM part is implemented and installed with the Microsoft Skype for Business/Lync installation, not with the Busylight software. If there are error messages in the DebugView log like:

  • Generic COM error or
  • Unable to cast COM object of type 'System .__ ComObject' to interface type 'Microsoft.Office.Uc.UCOfficeIntegration'

They will indicate problems within the COM configuration or the specific DLL or COM files. 

Unfortunately, Busylight cannot repair these issues, because they belong to the Skype for Business / Lync or Office setup. Repairing the Office installation can repair the COM issues in most cases.
However, a broken COM configuration sometimes fails to repair with this procedure. In that case, a complete reinstallation of the PC (including Windows) is required.


Still no luck: please contact us via the contact form or mail us at