原因：

证书问题，project和targets的证书都必须是开发证书，ADHOC的证书会出现此问题。

解决方案：

project和targets的证书使用开发证书。

其他：

failed to get the task for process XXX
This error happens when you have set Distribution Provisioning profile in code signing. Change it to Developer Provisioning Profile, then it will work. Worked for me for Xcode SDK 4.5.

把你的code sign由Distribution改成Developer.就这么简单.