CS:GO won't notify your Steam friends what server you're connected to if you're playing on a community server, but there is an easy command which will enable the function.
See the official Steam support page here
If you get this error message without have used any 3rd party applications, this quick fix should solve your issue.
None - Opt out of all beta programs
C:\Program Files (x86)\Steam\bin\Steamservice.exe /Install
Some people report that games run worse (not only CS:GO). It is also known that the AU update broke graphics card drivers.
Should be noted that an update for the game was released which added a warning for users who have XboxDVR enabled.
Download, extract and run this registry hack file.
Help & Options
Enable Developer Console (~)
Set Launch Options...
The console will now open when the game launches.