Cs 1.6 Client.dll Differs From Server -

Your Steam client is opted into a beta program that uses experimental files not yet adopted by standard public servers. Step-by-Step Solutions to Fix the Error Method 1: Verify Integrity of Game Files (Steam Users)

For players using non-Steam versions of the game (which are not recommended), the fix involves updating to the correct protocol version. Non-Steam clients and servers use a different file system, which is incompatible with official Steam clients. cs 1.6 client.dll differs from server

"Your .dll [my client] differs from the server's." :: Sven Co-op Your Steam client is opted into a beta