Learn how to troubleshoot Lync / Skype for Business


some questions I’m getting over social networks are “what do you recommend to learn Lync troubleshooting?” or “How to troubleshoot Lync?”

well, according to my approach regarding this subject, the simple answer is “understand Lync”, or as my colleagues describe me “you talk SIP”.

There are no step by step guides to troubleshoot every problem you might face in Lync, maybe you will find guides about troubleshooting most common problems like “Signing in” or “desktop sharing” or “inbound / outbound calls” but again, understanding Lync is the key, read about each server role, how to install it and how to configure each feature in Lync (could be a big task this one).

But that is not enough if you want to be more strong in troubleshooting then you need to learn SIP and SDP and as much of other protocols used in Lync as you can, learn how to use OCSlogger and Snooper, how to read the log files, understand them and locate the problem.

I have some articles in my blogs that might put you in the right direction, help you understand SIP, DNS records for Lync, security requirement…etc. the rest is your job to research.

Log files Locations

so first thing first where are the location of the log files of the different Lync clients? you need to know this, so you know how to collect the logs in a troubleshoot session

Client Logs location

Lync 2010 Desktop

Lync 2013 Desktop %userprofile%\app data\local\microsoft\office\15.0\Lync\tracing\
Lync Server SIP stack C:\windows\tracing\
Lync Web App %userprofile%\app data\local\microsoft\LWAPlugin\Tracing
Lync Mobile https://lyncweb.lyncdude.com/mcx/mcxservice.svc/mex
Lync Discover https://lyncweb.lyncdude.com/Autodiscover/AutodiscoverService.svc/root
Lync Office Web app https://wac.lyncdude.com/hosting/discovery
Lync Edge Replication https://<Edge server>:4443/ReplicationWebService


Note for Lync web app

add the following part to the end of the URL to enable full logging and generate a log file


so if you troubleshooting Lync online meeting e.g. meet.lyncdude.com you should have


the log file: LWAJSPersistentX.log where x is a number

Troubleshooting tools

so now to the tools that you can use to troubleshoot Lync starting with basic and up

Command Lines

so here we go with basics

  • Telnet (check if server listening to the required ports, also if port is open)
  • tracert (Check if traffic reaches its destination and not dropped in the middle by firewall)
  • pathping (same as tracert)
  • ping (check if the server is alive or if domain name resolve correct)
  • netstat (check opened/listening ports)
  • nslookup (lookup domain names and corresponding IP , Ports etc.)
Wireshark or MS network monitoring Tool

Wireshark or NETMON is two of the best network traffic sniffing tools out there, learn how to use them and they will help you big deal with troubleshooting Lync

Lync MVP Matt Landis has a great article on using Wireshark to troubleshoot Lync – give it a try

Event viewer

windows event viewer on Lync servers could provide good information about the problem and solution.

Monitoring server

great information can be provided and found in the Lync Monitoring server, specially when troubleshooting call quality issues, for example the Jitter value, packet loss…etc.


using the user activity Report and searching for specific call can give you good information about the media report of that call Jitter, package loss, MOS and many factors more.


OCSLogger & Snooper

your most important weapons against Lync problems are the OCSlogger and Snooper, download them from here

and those 4 videos by Microsoft Unified communication escalation engineers should explain to you how to use it

Lync Centralized logging

one of what I consider the best new feature in Lync 2013, the centralized logging, all you need to know about installing and using this tool is covered by Lync MVP James Cussen in his article “Lync 2013 Centralized logging deep dive”

Microsoft Connectivity analyzer

Microsoft Connectivity analyzer is a great tool help you test your Lync, you can test signing in from external network, or testing the Autodiscover services of your Lync

always keep it on mind


Lync Validator

this great tool by Lync MVP & Master Richard Brynteson can help you validate your deployment is right and meeting all requirements, the new version is also test it against POODLE.

Lync Best Practices Analyzer

I recommend running this tool usually after finishing with your deployment to check if Microsoft Lync best practices are met

Lync mobile analyzer tool

Lync client connectivity analyzer, help you troubleshoot Lync Mobile client sign in, it checks if all requirements are met to allow a client to successfully sign in for on-premises or office 365 deployment, you can choose the type of client you want to test, and if you testing from inside or outside the company network


Lync Pre-call Diagnostic tool

using the Lync Pre-call diagnostic tool will help easily troubleshoot call quality by checking three of the most important factors that could effect the quality of the call

  • Jitter
  • Packets loss
  • MOS

it is available for windows 8 and 7 in a desktop app or metro app


PowerShell command lines “Test-CS” family

create a couple of Synthetic transaction accounts and you are ready to go, using some PowerShell command lines you can test and troubleshoot Lync functionalities.

to get a list of the available Lync test command lines, open a Lync management shell and type the following command

Get-Command -Verb test -Noun “cs*”


and to create and prepare your Lync deployment for using those commands follow my previous guide here

Other tools

and more tools that you might some helpful, I know I did can be found in the Lynclab here

also check my guides on troubleshooting Outlook and Lync as well as Lync Federation


Author: Lyncdude

A Senior Service Engineer with more than 9 years of experience in Microsoft Exchange and Microsoft Lync Server / Skype for Business. Egyptian guy lives and works in Frankfurt - Germany. what is written in this blog is my own opinion and thoughts, not my employer and does not reflect their opinion

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