A Performance Center (PC) 11.52 System Health check shows the following error after installation of ALM Performance Center 11.52 Patch 1:
Database Connection Error: failed OpenConnection: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)
Checking the Database Connection String from both ALM Site Administration > DB Servers and Lab Management is successful. Note the MS SQL server for Performance Center is using a named instance (PC7) running on port 14345 (not the default port 1433) and the configured connection string is
jdbc:mercury:sqlserver:// < DB_Server_Name > \PC7:14345
To resolve the problem start the SQL Browser Service on the DB Server. This enables UDP port 1434 on the DB Server. PC Server then sends to the DB Server on UDP port 1434 and checks the DB server's response to complete the DB connection to the named instance and non-default port.