101-0502 is a very generic error, all it means is that your console failed to connect to something related to the friends service. It’s not even clear if the client passed authentication or not based on just this error. It can be caused by many things, some of which we can’t even control. Server load, bad environment settings, connection issues with your home network, etc.
There is no silver bullet fix because it’s caused by any number of issues. I’ve even had my console be unable to go online because of the interference caused by an external hard drive.