You have to verify the integrity of your game cache in steam. Now this may or may not be due to your files or a mod, but for some reason it involves some of your files, at least 2. It
should read the server files, but apparently it does not. If for any reason you need to validate files or make sure they're good files, this is the way to go. If you have errors, this can be a good place to start.
Open up Steam and goto your Games Library
Then right click on 7 Days to Die and choose properties
Then go to local files tab and verify the integrity of your game cache
You see the pop-up box, but also make sure at the bottom the files download before moving on.
Clicking the bottom message takes you here to see this...looks good.