Lync Web App opens instead of Lync client when connecting to a Lync meeting

Problem: When I click on Join Lync Meeting, Lync web app launches instead of using the Lync Application

Solution: This issue can be fixed in 2 ways

  1. Reinstall the lync client, thus fixing/reinstalling the missing or corrupted registry entries and file associations.
  2. Review and apply the correct registry entries/file associations.

We will address solution number 2 in this blog as it will help us understand what drives the association between clicking the “Join Lync Meeting” URL and launching Lync.

The “Join Lync Meeting” is simply a url. If there weren’t any registry entries or file associations involved, Internet Explorer would be launched. When Internet Explorer hits the lync meeting web page, the lync meeting page will launch the Lync Web App to join the meeting. In most cases if we have the Lync client installed, we don’t want this. Using the Lync client for Lync meetings produces a much richer experience.

If you’re running into an issue where Lync Web App launches where you are expecting to use the Lync client, it is likely something went wrong…

Here’s where to look

First place to comfirm is under Windows File associations.

Go to Control Panel > Default Programs and click on Associate a file type or protocol with a Program.

Look for the .ocsmeet extension/association and ensure that the default program that is opening it is Lync (desktop). If it isn’t highlight the extension and click Change Program, and select Lync (desktop) Click ok.

The second place to look is the registry. The usual caveat applies, backup your registry before making any major changes, buy beware, caveat emptor.

Open the Windows registry by running regedit (if you have permissions to do so). There are 3 places to check for registry entries.

  1. [HKEY_CLASSES_ROOT\ocsmeet_auto_file]
  2. [HKEY_CURRENT_USER\Software\Classes\ocsmeet_auto_file]
  3. [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.ocsmeet]

The Registry Settings




@=”\”C:\\Program Files\\Microsoft Office\\Office15\\Lync.exe\” \”%1\””


@=”\”C:\\Program Files\\Microsoft Office\\Office15\\Lync.exe\” \”%1\””





@=”\”C:\\Program Files\\Microsoft Office\\Office15\\Lync.exe\” \”%1\””


@=”\”C:\\Program Files\\Microsoft Office\\Office15\\Lync.exe\” \”%1\””






If the 32-bit version of Lync is installed  where you see ” C:\\Program Files\\Microsoft Office\\Office15\\Lync.exe\” it instead should be “C:\\Program Files (x86)\\Microsoft Office\\Office15\\Lync.exe\

You can reverse these registry entries forcing Lync Meetings to use the Lync Web App by removing these registry entries.


HKEY_Classes_Root.txt (994.00 bytes)

HKEY_CURRENT_USER.txt (1.17 kb)

HKEY_CURRENT_USERV2.txt (1.05 kb)

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