The old trick was to delete the ClientRegistry.blob file inside Steam folder. So close Steam, delete ClientRegistry.blob from Steam's folder and then start Steam and launch the game. Click to expand.
Same thing here. I have been playing since first day of beta, never had a problem, and since today I can't play.I tried the network settings too but it didn't change anything. Windows Firewall is disabled, I tried also disabling microsoft security essentials, same thing. I get the 'WARNING - Steam validation rejected - disconnected from server' every time.It's pretty annoying and I couldn't find any fix that works. I am not sharing my steam account and I have double step authentication so it couldn't be stolen either.I am glad I paid for the compendium.Would love some help.