GoldSrc Game Error: Wad file doesnt have WAD3 id

If you are getting an error about some wad isn't a wadfile, or it isn't the right type of wadfile then you need to either delete the offending external wad file in your game directory and replace it, or you need to delete your local content (GCF cache file) and re-download the content for that game.

Wadfiles contain all the texture images for maps. The .wad files for all the stock maps are inside the GCF cache files and wadfiles for custom maps are located in your game folder (so in cstrike for example).

Delete the Local Content

If this is a wadfile for a Stock map then you'll first want to check and make sure you don't have an old wad file by that name installed. Use file search to see if there is a file by that name in your game directories. If there is, then delete it or rename it and then see if you can play.

If you can't find a wadfile with that name then the file is inside one of your GCF cache files.

To delete the local content, go to the game that is causing you problems, so:

Steam > Games > then right-click on "Counter-Strike" (for example) and select properties.

There in that properties panel is the "delete local content" button

If you are having problems with CZ or CZ Deleted Scenes, then you may also need to delete the CS content or even HL content, this is the order:

CS:DS --> CZ --> CS --> HL

Each game in the sequence shown can use a resource that is in the following Game cache.

So if you have a CZ:DS problem and delete that content and it doesn't fix your problem, then delete CZ, then if that doesn't fix the problem, delete CS, and finally delete HL (you may have to Download HL first completely in order to delete it).

You will need to download the game content that you delete before you can play (click on the game).