How to fix Xcode 6.1 error while building IPA

I wish I knew why it works, but here's a fix that worked for me:

Found the fix !

Click on your project > Targets > Select your target > Build Settings >

Code Signing Resource Rules Path

and add :

$(SDKROOT)/ResourceRules.plist

The following patch for PackageApplications fixed it for me, I removed resource-rules as it says it's deprecated on 10.10.

Testflight builds work without it. Appstore builds too.

/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin % diff PackageApplication PackageApplicationFixed 155,157c155,156<     my @codesign_args = ("/usr/bin/codesign", "--force", "--preserve-metadata=identifier,entitlements,resource-rules",<                          "--sign", $opt{sign},<                          "--resource-rules=$destApp/ResourceRules.plist");--->     my @codesign_args = ("/usr/bin/codesign", "--force", "--preserve-metadata=identifier,entitlements",>                          "--sign", $opt{sign});

I emailed TestFlight support and got this response:

Our team is currently investigating this issue with the TestFlight Desktop app. In the meantime, please use Xcode to create the IPA file and then upload it using the desktop app or the TestFlight website.

The suggested workaround did work.