Yosemite Error – Sign in to Microsoft Lync Failed

Problem Summary

If  you’ve recently upgraded to Apple Mac OS X 10.10 Yosemite, and you attempt to use Microsoft Lync Mac 2001, you may likely get an error stating:

Sign in to Microsoft Lync failed because the service is not available or you may not be connected to the Internet.

This error message is misleading because the cause of it is likely neither of the problems suggested. Instead, it’s very likely due to having an additional language listed in your System Preferences.

Error Message Window

The error message window is like the one shown below.

Problem Solution

Follow these instructions to fix the problem.

1. Go to System Preferences – Available from the Apple menu.
2. Click on Language & Region – It is the flag icon in the top row of icons.
3. Make sure English is the primary language. If another language is listed, remove it. You need not close Language & Region settings for these modifications to take effect.
4. Try running Lync again. This time it should work.
5. You can now add the language(s) back in that you removed in step #3 above. Again, it’s not necessary at this point to close Language & Region settings. Try running Lync again. It should still work.
6. If you have another language selected as primary, such as Spanish, Lync won’t work. It will fail again as shown below.

Other Causes of Error

You may still get the connection error even after using the work-around fix described above. This can happen if your computer has gone into sleep mode, and then you wake it up. Just click the Sign In button again and it should connect.

User Experience Feedback

From Greg Johnson (17 Dec. 2014):

I was unable to start Lync. Here’s what I did:

1. I checked my default preferred language in settings at it was already set to English.
2. In an effort to clear out any previous settings, I added French and set it to the default.
3. I tried starting Lync, but it still wouldn’t load.
4. Then I removed French and returned to English as the default.
5. Lync works fine now.