I can't connect to game servers

[OldMan]

I can't connect to game servers after the last update. It gives the error 'cannot connect to the server, the AppID specified by the server is invalid'. How can I solve the problem?

[Marble]

You should ask on the discussion page for whatever game you're talking about.

Mostly likely the server has not updated yet, both server and client need to be running the same version

[OldMan]

The problem has nothing to do with a single game! For example, while before I could easily connect to any server from the BattleMetrics site, now it gives this error and does not connect!