We just want to let everyone know that we are aware of the issues affecting the servers. These issues are affecting all Source mods and Valve has been notified.
Server owners should know that there are some possible temporary fixes:
We found a workaround for server admins until Valve fixes the issue:
Note: This fix is for Windows servers only. No idea if something similar works on Linux.
1. Use steamcmd to install SDK Base 2007. It won't work with the old HLDSUpdateTool.
2. Download the Steam client on the server machine and run it until you get to the login screen. You don't need to log in with an account, just leave Steam running at that screen.
3. Start your dedicated server
The server should work like usually now. Hopefully Valve fixes this soon.
It's possibe that listen servers are also working, and that this is only affecting dedicated servers.