Between the missing files and running Setup.bat, did you start fresh with a new untouched directory tree? Since I’ve always run Setup.bat right away I wonder if maybe something could have gotten wacky in there and when it scanned for dependencies it got confused.
I decided to try building engine from the source. First thing that happened is that I got error that I don’t have all the files. Turned out UE4 docs don’t say a thing about dependencies.
After running Setup.bat and getting 99% of the dependencies, I got this error:
Failed to download ‘http://cdn.unrealengine.com/dependencies/2636758-e606e606851e4693b1729dd35dcef7ae/345f37ad429b27f1360cf26aa535ef037724f7c4’: The specified path, file name, or both are too long. The fully qualified file name must be less than 260 characters, and the directory name must be less than 248 characters. (PathTooLongException)
After generating solution and building UE4 I got this error:
No. I ran GenerateProjectFiles.bat, got error, ran Setup.bat, generated solution, but ended up building with an error (added it to my OP).
That build error is from the C# stuff, which are tools that help build the engine. Considering how delicate UE4 can be, really I think you should try the whole install process from the very beginning. Get a fresh copy of the source tree into its own directory, run Setup.bat, allow prerequisites when asked. When that is done, run GenerateProjectFiles.bat and then try building the engine. If you still have an issue we can dig deeper – or you could go with 4.15.1 in case this is a recent bug no one has seen yet.
I started clean, renamed root folder to have a short folder name, ran Setup.bat first, then GenerateProjectFiles and all went well.
These errors can be solved by using Long Path Tool program.