The pre-4.16 builds are rather old by now, and even Epic doesn't really support them any longer, officially.
Is there a specific reason you need to use such an old version of the Unreal Engine? If there is, I can *try* to debug it based on your logs and the vmf file, but if it imports fine in a newer version...
It works beautifully in 4.18, but I'm trying to import my work into PavlovVR (which appears to be built in the 4.15 version of the engine, or the template for it is). I would be happy to import the assets into 4.18 and migrate them to a project from older version but that doesn't seem to work either.
If it helps, the project log hits me with with "Failed to load ANSI text file: [users/x/x/x/x/x/x/x] materiallist." before crashing. I also tried rebuilding the masterlist but that didnt help either.
If there is another way to work around this, I'm open to suggestions.
Also, you can d/l the .bsp from here:
Do you have non-basic a-z 0-9 (so accented, asian, whatever) characters in the directory names/file names/material names?
I flipped through them all and didn't notice any unusual characters in the names.
Hm. Try putting your project in a directory closer to the root of a drive (so c:\projectname or something), see if that helps.