When you use Microsoft Skype for Business Server 2015 Persistent Chat Server, you may receive the following event:
Source: LS Persistent Chat Server
Message: The Persistent Chat database connection was lost.
The Skype for Business Server 2015, Persistent Chat lost connection to the database using connection string:
Data Source=sql.contoso.com;Initial Catalog=mgc;Integrated Security=SSPI;
Cause: An unexpected error occurred that caused the loss of the Persistent Chat database connection.
Check the state of the database.
This issue occurs because the procProcessADUpdates stored procedure takes more than 30 seconds to run. Default Skype for Business Server 2015 Persistent Chat Server time-out is 30 seconds so that the stored procedure execution will be aborted.