Which branch were you attempting to use (master, release, etc)? The master branch has not had any testing and often can be unstable. Additionally, which version of Visual Studio are you using to compile the engine? If you’re compiling 4.12, please make sure that you are using VS2015. Also, if you are compiling for the first time, make sure that your solution configuration and solution platform are set to Development Editor / Win64 respectively.
We have not heard back from you in a few days, so we are marking this post as Resolved for tracking purposes. If you are still experiencing the issue you reported, please respond to this message with additional information and we will offer further assistance.