invalid Toolchain. New apps and app updates must be built with the public (GM) versions of Xcode 6 or later, and iOS 8 SDK or later. Don't submit apps built with beta software.

앱 개발을 완료하고 앱 검수를 위해 앱을 업로드한다. 그다음 "심사를 위해 제출"을 누를 때 위와 같은 오류가 뜬다면 나의 경우 아래와 같이 해결했다.

원문 : http://stackoverflow.com/questions/32174954/submitting-app-from-building-in-xcode-6-4/32233429#32233429

Apps that you submit should be developed using the latest version of Xcode from the Mac App Store and should be built for publicly available versions of iOS, OS X, and watchOS — except when GM seeds are available. Now Mac App Store's Xcode is 6.4 and OS X Yosemite is Build 14F27. If you user xcode 6.4 on OS X El Capitan, you should follow the steps:

1. Using Xcode, then archive your project
2. Open organizer, find your .xcarchive file 
3. Right click the xcarchive file, choose [Show package Contents]
4. Find Products/Applications/XXX.app/Info.plist
5. then change [BuildMachineOSBuild] value to 14F27, just like this: 
6. Now, you can go to Xcode->organizer, then 【Submit to App Store】