Skype for Business Client Side Tracing

At some point during troubleshooting the Skype 2015 client, we might have been asked to recover the client side tracing logs for an administrator.  Or if you are the administrator you might have asked users or other IT personal for this client logs.  Sooner or later, an end user is bound to ask you, “Which log files do I get you?” If there are multiple UCCAPI log files then the question becomes, “Which of UCCAPI log files are you needing, for I see several of them?”  Let’s take a quick look at a few areas of importance regarding those Skype for Business 2015 client side log files.

Note:  This article can apply to Lync 2013 client side logs as well.

Client Side File Location

Let’s begin by pointing you in the right direction of where the UCCAPI client side logs are located. There are two different locations, and that depends on the client version that you are running.  Both log paths for Lync 2013 and Skype 2015 are noted below:

  • For Lync 2013 (Skype for Business) %userprofile%\AppData\Local\Microsoft\Office\15.0\Lync\Tracing
  • For Skype for Business 2015 %userprofile%\AppData\Local\Microsoft\Office\16.0\Lync\Tracing

Turning on Logging through the Registry

Enabling logging through the registry is a bit antiquated, but I figured I would add the location just in case

some feel the need to do so. I have added the registry paths below for both Lync 2013 and Skype for Business client as well.

For Lync 2013, pull content from the following registry subkey:


For Skype for Business 2016, pull content from the following registry subkey:

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Lync Note: Keep in mind that logging is enabled out of the box for the client and the logging level is at low.  The logging level of the client logs can be modified by modifying the client policy.

Figure 2: Logging Level  

How Many Logs Files is Sufficient?

When looking for the correct log file its important to know how many files you should be expecting in the file directory.   What we can see below in figure 3 is that I have specified in the registry that the MaxFiles Data value is set for “3”.  What this will do is make sure that I have 3 UCCAPI log files as seen in figure 1. The MaxFileSize Data value is set for 52 Mb, which means the log size of each UCCAPI log file will not grow above the configured specified size. Figure 3: Registry values 

What is Standard Practice?

Out of the box you will have a configuration of 3 UCCAPI log files in the tracing folder.  In addition each of the log files will not exceed the default size of 52 Mb.   You might not want to deal with the 3 log file approach and rather just deal with a single UCCAPI log file.  Keep in mind that the file will overwrite itself in a frequent manner that doesn’t prove to be too helpful with troubleshooting.   I personally leave the default settings regarding the MaxFiles and MaxFileSize the same.  As for the level in which verboseness and detail of the log files, that setting is personally recommended to be set at Full

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