Xcode build & run error: “Process launch failed: Failed to get the task for process 216”

Question

After updating to Mavericks and making sure I got the latest updates of Xcode installed as well, Xcode suddenly fails to launch apps on the device.

It installs the app o

Answer 1

In my case I had to go to Keychain, lock/unlock or unlock/lock Login, there is something with the signing that looses state.