"Lync was unable to sign in" error message when you try to sign in to Lync Online by using Lync for Mac 2011 in a Mac OS

Applies to: Microsoft Lync Online


Assume that you set the system time zone to your current time zone on a device that is running a Mac OS. When you try to sign in to Microsoft Lync Online by using Lync for Mac 2011 on the device, the operation fails. Additionally, you receive the following error message:
Lync was unable to sign in. Please verify your logon credentials and try again.

  • This issue occurs when your current time zone is the Pacific Time zone or a time zone west of the Pacific Time zone.
  • If you change the system time zone to a time zone east of the Pacific Time zone, you can sign in to Lync Online by using Lync for Mac 2011. For example, you change the time zone from the Pacific Time zone to the Eastern Time zone.


This issue occurs because Lync for Mac 2011 incorrectly reads the system time. Therefore, the web ticket that Lync for Mac 2011 tries to use is expired.


To resolve the issue, install the following cumulative update:
2778095 Description of the Microsoft Lync for Mac 2011 14.0.4 update

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.