At TotalView startup, the OS checks whether the Mach system call -task_for_pid() is working properly. If the call returns an error, no debugging is possible, and TotalView outputs an error message that begins “The Mach system call -task_for_pid() is not working properly.” TotalView cannot distinguish the circumstances that can lead to this error, which are varied and depend on the version of OS X. The following sections describe a series of steps to troubleshoot this problem.