It looks like the following command was not properly executed for the WebSecurity.plugin file: sudo chflags nosappnd /Library/Internet\ Plug-Ins/WebSecurity.plugin Note that you need to copy that exactly as-is, rather than trying to re-type. My guess is that you may have tried to enter that command manually and left off the '\' character, which would prevent the command from working properly. (The '\' is needed due to the space in the folder name. A space is not allowed in a path in Unix