An extra note – how to find the CleanThirdPersonServer.Target.cs file: Select your project folder and Ctrl+F to Search Target.cs (or type in the whole file name), then open the file it finds in notepad.
For Substance Designer fans — Since Substance plugin is now installable for v4.8 from the marketplace for projects (without having to use github), if you added the earlier plugin to your project you will need to remove the /plugins/Substance folder from the MMOKit to avoid an Already Exists error.