S3: Client connected with invalid ticket: UserID XX

Hello, my server gets this in console S3: Client connected with invalid ticket: UserID XX. What may be wrong, is it the server or the client who tried to connect? O,o

Steam ticket / auth issue; delete the clientregistry.blob and re-login to steam.

So it isn’t serverside issue?

It may also happen if the server can’t communicate with Steam, I believe… But, I think most of the time it is a client issue.