I just ran in to this problem when I created a new project and tested it in iPhone. And I did not get this error when I ran the app in Simulator. So I guessed the problem was with the certificates or provisioning profile. Then after little bit of googling I spotted the problem . My Project Name had a question mark(?) in it. And this had created the problem. And one other friend had reported the same problem when he used plus symbol (+) in this threadhttp://www.iphonedevsdk.com/forum/iphone-sdk-development/21988-xcode-issue-signed-resource-has-been-added-modified-deleted.html .But the simulator did not throw me any problem. So it is always good to check your app very frequently as you progress in your App development.