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Unable to log in to Lync 2011 (Mac OS)

Note: This article is useful if you are:
  • Unable to log in to Lync 2011 and are confident your credentials are correct.
  • Experiencing oddities using Lync.

Note: This issue does not occur in Skype for Business for Mac. If you have OS X 10.11 or macOS 10.12, you can install Skype for Business for Mac from Self Service.

Resolve the log-in issue

  1. Quit Lync (do not just minimise it).
  2. In Finder, click Go.
  3. Hold the Option key > Library > Preferences.
  4. Move the file com.microsoft.Lync.plist to the trash.
  5. Open the ByHost folder.
  6. Move the file MicrosoftLyncRegistrationDB.plist to the trash.
  7. Launch Lync to see if the issue you were experiencing has been resolved.


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