That happens when you start the patcher without the necessary changes made to your environment. The patcher tries to connect to http://services.lego.com where it doesn’t find anything LU related anymore, so it gives out that error. The easiest way around this, is to open the folder your client is stored in, and open the “client” directory and then start “legouniverse.exe”. You may need to adjust boot.cfg to connect to a server of your choice.
When you use the client you used when the game was live, you might need to download a full version (~10GB), e.g. nexus2 or the BlastClient, which are both complete enough for mostly stable gameplay.