GET https://ServerName:443/ HTTP/1.0?

Let's back up a little. Where did you see this command? You probably saw it in a DataSource. In that case, the DataSource is not complete. The DataSource should be modified in a way that it's sending the right request to each device, instead of sending the same request to each one. By sending the same request to each device, the request is failing (because it's malformed). That failure is causing an alert to be opened by that DataSource.