I'm just installing SilverStripe. I had 3.6.2 working on a Windows 2016 server, PHP 7.1 and Apache 2.4. I decided to try out 4.0.0 Beta 3, so I deleted 3.6.2 and started from scratch, same directory name, everything else the same. The install script for the beta said that friendly urls weren't working, check mod_rewrite and so on. I re-checked, and it was still setup properly in Apache. So I deleted the beta and reinstalled 3.6.2 from scratch again, same directory, and it works fine. I don't think I'll continue with the beta, but just wanted to let someone know.