Xcode : failed to get the task for process
This error tends to appear when you pick an ad-hoc provisioning profile. Make sure that your code signing is for development.
This error happens if you have used a Distribution Provisioning Profile for debugging to device.
Go to Build Settings > Provisioning Profile and set to 'None' for Debugging.
I finally solved this by remembering to set code signing and provisioning parameters in BOTH project and target tabs...