Could not connect to the following SQL Server: 'XXXXXX-SQL02'. Verify that the server is up and running and that you have SQL Server administrative credentials. [DBNETLIB][ConnectionOpen (SECDoClientHandshake()).]SSL Security error.
Having never seen this particular error, I resorted to my friend Google who led me down a wormhole or possible issues and resolutions related to certificates and protocols. Turns out that this was indeed related to a security protocol – TLS 1.0 to be exact. It was disabled on the SQL Server as part of our new security template for new servers. So with the help of one of Cloud Application Engineers, Spencer Ashworth, we enabled TLS 1.0. This is done through a simple registry change.
Browse to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.0\Server\ and locate the DWORD named Enabled. Set the value to 1, close the registry and then reboot the server.