Error: The Xcode build system has crashed

When you build project xcode and got this error.

So, this error usually happens between Xcode major versions. Apple usually claim their new build system is ** times faster than their previous version. If you see this error(I see this on changing Xcode9 to Xcode10 beta), you can always change it to the legacy build system. Here is how you can do this:
Change build system to 'legacy':




and then rebuild your project with no error.