Fabric release Xcode 6.3 codesign xcode-select

If you have multiple versions of Xcode installed on your system you may need to ensure the command line tools are set for the version of Xcode you're attempting to build from.

Navigate to "Locations" in Xcode preferences (select Xcode from the menu bar, then "Preferences..." then "Locations"). In the drop down next to "Command Line Tools:" select the version of Xcode you're using and then attempt a build.

Mike from Fabric here.

1) To clear that error from Fabric.app: Quit Fabric.app, then run this command to clear the local cache:

rm -rf ~/Library/Caches/com.crashlytics.mac

You may also need to clear:

rm -rf ~/Library/Caches/com.crashlytics
rm -rf ~/Library/Caches/com.crashlytics.data
rm -rf ~/Library/Caches/com.crashlytics.run

Then restart Fabric.app and you'll be all set!

2) To distribute outside of Fabric.app, use either method mentioned here.