Swift command line tool runtime crash dyld: Symbol not found: __pthread_atfork_child

Question

When I build any swift command line tool it always crashes (Thread 1: signal SIGABRT) right after launch with:

dyld: Symbol not found: __pthread_atfork_child
  Referenced from: /usr/lib/libSystem.B.dylib
  Expected in: /usr/lib/libSystem.B.dylib
 in /usr/lib/libSystem.B.dylib
Program ended with exit code: 9

This happens to any command line tool I build. Even when I build the xcode command line tool template.

Reseting the mac to an earlier time machine backup fixed the issue for a day. Then it came back for no reason. However I am able to build command line tools using the swift cli and package manager.

I'm using Xcode 8 on macOS 10.12.5

Answer 1

I'm experiencing the same issue. For me a workaround was to edit the scheme an uncheck the "Queue Debugging: Enable backtrace recording".