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Consider the following scenario:

  • You create a new user in a Microsoft Lync Server 2010 environment.

  • You enable the user for Lync 2010.

  • The user principal name (UPN) of the user is changed.

In this scenario, the user cannot sign in to Lync 2010 even by using the correct logon credentials. Additionally, the user receives the following error message in the Cannot sign in to Lync error window:

Lync was unable to sign in. Please verify your logon credentials and try again. If the problem continues, please contact your support team.


This issue occurs because the Session Initiation Protocol (SIP) uniform resource identifier (URI) of the user is not updated when the UPN of the user is changed. Therefore, the SIP address does not match the UPN when the user tries to sign in.


To resolve this issue, install the following cumulative update:

2670326 Description of the cumulative update for Lync 2010: February 2012
Note After you apply the update, the user will receive the following error message:

New sign-in address? Looks like the sign-in address you entered doesn’t exist. You can try a different sign-in address or contact support to update your sign-in address in the system.

More Information

For more information about the SIP URIs, visit the following Microsoft website:

General information about the SIP URIs

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