Cause

This error means that the xinit(1) program, which sets up X11 resources and starts a window manager, failed to locate the X server process. Perhaps the user interrupted window system startup, or exited abnormally from OpenWindows (for example, by killing processes or by rebooting). The X server might have crashed. Data loss is possible in some cases. Depending on the process timing, this message might be normal when the OpenWindows environment exits during a system reboot.