Error "A connection was successfully established with the server, but then an error occurred during the login process. (provider: Shared Memory Provider, error: 0 - No process is on the other end of the pipe"
Solution:
This is login authenticate problem. Please check the following things:
- In the SQL Server Properties, please check that "SQL Server and Windows Authentication Mode" is enabled, if not enable, please enable and restart the SQL Server.
- Is Login have the permission to particular Database?
- This might be a firewall issue as you mentioned it only happens when security agent installed. Please make sure you have properly configured security agent to allow Database Engine Services accesses.