我也遇到了下面的错误:
2015-08-10 18:52:28.769 instruments[59132:942138] WebKit Threading Violation - initial use of WebKit from a secondary thread.
2015-08-10 18:52:30.608 instruments[59132:942124] Automation Instrument ran into an exception while trying to run the script. UIAScriptAgentSignaledException
2015-08-10 10:52:30 +0000 Fail: An error occurred while trying to run the script.
Instruments Trace Complete (Duration : 1.999696s; Output : /Users/lenovo/instrumentscli8.trace)
看到楼上说是设置的问题,尝试了一下,解决了,解决方法贴出来供参考:
打开手机中 “设置”->"开发者”,将 Enable UI Automation 打开,即可。