Vapor build failure

Question

I am using Mac with Sierra OS (10.12.5). I Installed Vapor using home-brew. If I tried to run command 'vapor build' in terminal it shows following error.

No .build folder, fetch may take a while...
Fetching Dependencies [  •                      ]
Error: backgroundExecute(code: 1, error: "swift-package: error: unknown command: --enable-prefetching\n", output: "")

Please help me.

Answer 1

If you installed latest xcode and still getting error.

Goto: xcode -> Preferences -> Locations -> Command Line Tool

Change it to latest. Then check swift version. Then try vapor commands.

Answer 2

Looks like you are running Swift 3.0, where as the toolbox (and Vapor 2) required Swift 3.1.

Upgrade Swift to 3.1 (by upgrading Xcode usually) and it should work.