When trying to start the Trados GroupShare Application after a few seconds this stops. According to the application logs the error message indicates there is an issue with the connection between Trados GroupShare Application server and the SQL server.

The error message stored in the Trados GroupShare ApplicationService.log file:

System.Data.SqlClient.SqlException: 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: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server) ---> System.ComponentModel.Win32Exception: Access is denied

In this particular case, the firewall from the SQL server was blocking all connection attempts to the SQL Server.
For example: pinging the Trados GroupShare Application Server from the SQL server did not work and ended in Request Timed out.

The connection from Trados GroupShare Application server to the SQL server is no longer available because:

1. The SQL Server no longer accepts connections 
2. The SQL instance defined in Trados GroupShare Console / Databases is incorrect
3. The SQL services are stopped.



*The screenshot is taken from Trados GroupShare 2015

Useful info can be seen here: https://docs.microsoft.com/en-us/sql/database-engine/configure-windows/troubleshoot-connecting-to-the-sql-server-database-engine?view=sql-server-ver15