CS 1.6 ERROR: Failed to initalize authentication interface. Exiting

Failed to initialize authentication interface. Exiting

This error generally occurs when you have participated in "beta" version of new update which is not fully supported.
Therefore, this error occurs when your system is not able to play the "beta" version of the game.

This is a general error which occurs when you go for beta update of CS 1.6.

As they are "beta" updates, so there are not such a stable version, 

so if you see this error it takes 2 minutes to solve this problem and this is how you solve it.

SOLUTION:

1. Open  Steam, goto account tab.
2. Click on "change in Beta participation".
3. Select "none".
4. Click OK and restart Steam.

You are Done.

Still if you face any problem comment below.

CS 1.6 ERROR: "Couldn't find 'decals.wad' in DEFAULTGAME search path."

ERROR in CS 1.6 : "Couldn't find 'decals.wad' in DEFAULTGAME search path."

Sometimes playing on servers that changes your files and next time you start your game you
end-up into an error "Couldn't find 'decals.wad' in DEFAULTGAME search path."

So always play on a secure and good server which do not modify your content or just make all your files in "cstrike" folder as read only mode.

This is a very common error that occurs if "decals.wad" file is missing.

There are many chances that this file is found missing but the solution is simple, just follow following steps:

⇩ DOWNLOAD FILE

• Mirror: https://www.dropbox.com/s/54zbcizclx1udt6/decals.wad?dl=0

- Download file "decals.wad"
- Copy it into your cstrike folder:

•  For STEAM: C:/ProgramFiles/Steam/Steamapps/common/HalfLife/cstrike 

•  For NON STEAM:C:/ProgramFiles/Valve/Counter-strike/cstrike 

- Restart your CS and your problem is solved.