We’re investigating an emerging issue with Skype Directory Search for Skype for Business On-Premises to Skype Consumer chat capability. When searching for a Skype account in the Skype for Business Client, you might get the following error message:
An error occurred during the search. Please try again, and contact your support team if the problem continues.
Additionally, you may find the following error in the Lync event log on the impacted Edge servers:
Log Name: Lync Server
Source: LS Web Components Server
Date: 1/13/2020 8:53:26 AM
Event ID: 4106
Task Category: (1074)
The server selected for next hop could not be reached, or did not reply.
A server selected as a proxy target for HTTP traffic could not be reached or did not reply: skypegraph.skype.com.
Performance Counter Instance:
Failure occurrences: 4, since 1/13/2020 4:51:18 PM.
Failure Details: WebException: The underlying connection was closed: An unexpected error occurred on a send.
Cause: The remote server may be experiencing problems or the network is not available between these servers.
Examine the event logs on the indicated server to determine the cause of the problem.
Based on our initial investigation it appears that the Skype Directory Search endpoints are refusing TLS 1.0 connections.
To fix this issue you need to enable your Edge servers to use TLS 1.2. Your Lync or Skype for Business Servers may require dependency updates, including .Net framework updates. All the requirements for enabling TLS 1.2 are documented here:
Note, this procedure is also supported on Lync Server 2013, for more information refer to the following blog post:
Once all the pre-requisite software updates are completed, you then need to deploy the prerequisite registry keys. This will enable your Edge servers to negotiate TLS 1.2 connections to the Skype Graph web service endpoints. You do NOT need to disable TLS 1.0 on the impacted Edge servers.
Microsoft is aware of this issue and continues to investigate. We will update this post with additional information when it becomes available.
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