I have an application that I am debugging on iPad. 2 days ago I wanted to debug a same updated application but I am having this error.
The identity used to sign the executable is no longer valid.
Please verify that your device’s clock is properly set, and that your signing certificate is not expired.
(0xE8008018).
I don't have iPhone Developer certificate yet, but I have debugged this game once.
Try restarting XCode. It worked for me.