The message "Invalid session (Try restarting your game)" does not take into account the fact that many people choose to keep the game launcher open or hidden while the game is running. In such a case, the invalid session can only be fixed by restarting the launcher itself, or by switching user from within the launcher.
If someone who keeps their launcher open sees this message, and fails to resolve it having only restarted the game but not the launcher, they might create unnecessary issue reports.

A suggested replacement message has already been submitted by me for each variant of English on the Crowdin project, but United States English will require changes in the source language by developers.