In my last post, I mentioned a co-worker alerted me to problems with file transfers in Skype for Business failing.

I did promise to do a post on her situation once we resolved the issue. Well, we resolved it!

I documented the troubleshooting steps we took. Many didn’t help our problem, but they might help yours. Like most technical issues, what fixes one instance may not fix another.

The Problem: Skype for Business Locks Up When Files Sent to the User

From the co-worker’s original email:

“Almost every time someone sends me a document through Skype [for Business], it locks up. I have to shut it down through Task Manager. It’s happened since Lync, and was never fixed. Not sure what it is, but maybe you could find something on it?”

A very specific circumstance. What happens if she sends files through Skype4B? According to her, it would work sometimes, but not always.

File Transfer Troubleshooting Steps

First, make sure file transfers are enabled for the user! I covered this in the last post, under the “When to Turn File Transfer Off” section. All the troubleshooting in the world won’t help if your user has file transfers disabled.

Now, assuming file transfer is enabled (it was for the co-worker), let’s proceed with troubleshooting.

Step 1: Check the Logs for Errors

On a Windows system, you’ll find system logs in the Settings (Windows 10)/Control Panel (Windows 7/8).

The Skype for Business client also records logs, if you have it set up to do so. Here’s how to check that.

  1. In the Skype for Business client, click Tools –> Options.
  2. The Options window will open, showing the General Options. In the third box, titled, “Help your support team help you,” you’ll see two logging options. One is a dropdown menu titled, “Logging in Skype for Business” with three choices: Off, Light, and Full.
    • This was pre-set upon install, but you can change it with a click. We set all customers to Full by default.
  3. Where do you find these logs? In the Tracing folder. You’ll find this at “C:\Users\YOURUSERNAME\AppData\Local\Microsoft\Office\[16.0 or 15.0]\[Skype for Business or Lync]\Tracing.
  4. The other logging option is a checkbox for, “Also collect troubleshooting info using Windows Event Logging.” This tells Skype for Business to feed logging data to Windows’ event logs.

Turn on Logging in Skype for Business

Event Logs for Skype for Business

We pored through these logs. I found several instances of Skype4B starting properly, closing properly, one or two “Error: Improper Shutdown” messages…but no explicit file transfer issue. The shutdown errors could have been the file transfer freezing Skype—but they could also have come from my co-worker force-quitting after the freeze.

Once we knew her logs were running, we tried a test. I sent her two files via Skype4B Conversation – a simple image, and a big Word document. Of course, Murphy’s Law being what it is, they worked perfectly!

While we waited for another instance of the error, we tried the next step.

Step 2: Run Diagnostics

Next, we ran DirectX Diagnostics (dxdiag.exe).

Now, I know what you’re thinking. This has nothing to do with Skype for Business. Why even try? Normally I wouldn’t have…but my co-worker said something that prompted us to. She said she recalled the screen flickering when the freeze occurred. Not always, but often enough that she remembered.

That could indicate a video issue. Quick, easy (and built-in) way to check for those is DirectX Diagnostics.

Running DirectX Diagnostics is simple on any Windows PC. Click Start, and enter “dxdiag” (no quotes) into the search box. Click the “dxdiag.exe” result.

The DirectX Diagnostics tool opens up, and runs a scan on your video and sound components. If all’s well, you’ll see results like this:

DXDiag Screen

Which we did. On to the next idea.

Step 3: Third-Party Block

If file transfer is enabled, and the client appears not to have any serious problems…was something ELSE blocking Skype for Business file transfers?

I turned to Almighty Google to check. Soon enough I found a possibility—Malwarebytes. If Malwarebytes Home or Premium is running, it could see Skype for Business file transfers as a malware vector, and block them.

The solution? Updating the Skype for Business client. More on that in a moment.

There’s also a workaround: adding Skype for Business as a “Web Exclusion” within Malwarebytes*.

  • Open Malwarebytes.
  • Click the Web Exclusions tab.
  • Click the “Add Process” button.
  • Enter the Skype for Business .EXE file path.
  • Save, and restart the computer.
Malwarebytes Web Exclusion
Web Exclusion set for Skype for Business in Malwarebytes Premium.

Skype for Business 2016 freezes on a computer that has Malwarebytes is installed – Microsoft Support

*IMPORTANT: This does NOT work on all versions of Malwarebytes. Check your version.

We use a corporate site license for our Malwarebytes, so users don’t have admin control on their local machines. Including my co-worker’s. Next!

Step 4: Video-Based Screen Sharing Getting in the Way?

I came across this troubleshooting idea in a very roundabout manner. Several support threads and some comment-sifting brought me to a comment on a Jeff Schertz blog post from 2015. The post is on Video-Based Screen Sharing (VBSS), an improvement to Skype for Business’ screen sharing capabilities.

The post itself is stellar. But how does it relate to file transfer freezes? That comes from a comment left by “Tsuyoshi” in March 2016. They gave a way to disable VBSS via two registry edits. Jeff added them to the post under an update at the bottom.

For 64-bit Skype for Business on a 64-bit Windows OS:
[HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Lync]
“EnableP2PScreenSharingOverVideo”=dword:00000000

For 32-bit Skype for Business on a 64-bit Windows OS:
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Office\16.0\Lync]
“EnableP2PScreenSharingOverVideo”=dword:00000000

Value must be set to zero.

According to some other commenters, VBSS had interfered with file transfers on their computers. Disabling it, as with this registry edit, fixed the problem.

We tried it. Unfortunately, it didn’t help. But we did finally get an error message related to the file transfer freeze!

When we saw that? Well, we knew what to do then.

Step 5: Does the Skype for Business Client Have All its Updates?

Spoiler: This is what solved the problem.

As with pretty much all software these days, you need to keep Skype for Business up-to-date. Windows as well (as we’re unfortunately seeing with the WannaCry ransomware attack).

surprised dog photo
OH NO! Photo by mdalmuld

We have Group Policies in place to control updates & patches. But it turned out that this co-worker had recently replaced her computer with a new one. We’d imaged her last computer, and loaded the image onto the new one.

In the process, she somehow missed out on the latest updates.

Once we found that out, we quickly applied all available updates related to Skype for Business. I don’t know which of these two updates fixed the file transfer issue…but one of them did!

  1. Skype for Business Update KB3115087 (June 2016)
  2. Security Update for Skype for Business KB3191858 (April 2017)

Full List of Recent Skype for Business Updates (in case you need them!)

After a reboot, we repeated the tests. Every file, from Word to PDF, came through without a trace of freezing. We have a very happy co-worker right now.

Step 6: Uninstall/Reinstall

When all else fails, try uninstalling the Skype app entirely & reinstalling fresh. Tedious and frustrating, but like updates, sometimes it’s critical.

We did not need to uninstall/reinstall Skype for Business in this case. But I’m putting it in as the last step, because that’s where it should be in troubleshooting efforts. If a simpler option is available, take it.

Supporting Skype for Business is complex. This should make it a little easier.

I wrote these in steps for easy reference. They aren’t necessarily linear, or even necessary to all troubleshooting cases. For instance, about a year back we had a customer with a consistent error—every time he left a Skype Meeting, the client would crash. Checking the system logs immediately told us the cause: severe delays in the client’s responses. Which led straight to an uninstall/reinstall.

Whether you’re a frequent reader or you just dropped by from Google, I hope these steps help speed up your support process!

What Skype for Business support issue did you have the hardest time with? Please comment or email. (Venting is OK…so long as you fixed it!)

By the way, I’m still testing the third-party app I mentioned in the last post. A review post is forthcoming, but I want to run the app through its paces first.

Troubleshooting Reference for Skype for Business File Transfer Issues
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