[quote='798802022, DTS Engineer, /thread/761331?answerId=798802022#798802022'] The "/" volume should include NO user information AT ALL and, ideal, should minimize any kind of "configuration specific" data. [/quote] This is perfectly achieved with a simple directory /var inside / volume (RO ) and a bucket of symbolinc links ( the traditionnal one ) pointing to directories inside the var volume ( RW ) mounted on /var, as exposed in my OQ. As a concrete example, there is a need to clearly separate system applications ( RO ) and user installed applications ( RW ), this is achieved throught the use of 2 different clearly distinct directories and one preconfigured symbolic link inside / ( RO ⇒ non modifiable ): User visible path real path to volume ------------------------------------------------ /Applications /Applications / /local/Applications /var/Applications /var And that's all folks! Thus my OQ stands: why didn't Apple choose such a basic, simple and efficient construct with just 2 basic volumes? Real life teach us everyday that complexity is one of the biggest enemy of performance and security.

This is neither a user, nor a developer issue. This is a kernel issue. I am working on this one, and I would like to understand it. Back to the initial question, where is documented the error code -3905? I got it repeatedly in an environment of work after about 6 days of full load of the Wi-Fi network with 4 clients moving. Here is the typical track I get once the network is unusable for everyone end Wi-Fi Logging turned to on on one of the client Mac. Notably, iPhones and another Mac cannot reach anymore the network once this error appear. Sun May 22 10:45:37.994 Driver Event: <airportd[246]> _bsd_80211_event_callback: APPLE80211_M_ROAM_START (en0) Sun May 22 10:45:37.994 Info: <airportd[246]> Roaming started on interface en0 Sun May 22 10:45:37.994 Info: <airportd[246]> PRIORITY LOCK ADDED [client=airportd, type=4, interface=en0, priority=5] Sun May 22 10:45:37.995 Info: <airportd[246]> SUSPEND AWDL for interface en0, timeout=10.0s, reason=Roam, token=166 Sun May 22 10:45:37.995 Info: <airportd[246]> RESUME AWDL for interface en0, reason=Roam token=165 Sun May 22 10:45:37.995 Roam: <airportd[246]> Unschedule roam RSN handshake timeout, received ROAM_START Sun May 22 10:45:41.106 Info: <airportd[246]> PRIORITY LOCK REMOVED [client=airportd, type=4, interface=en0, priority=7] Sun May 22 10:45:41.106 Info: <airportd[246]> RESUME AWDL AFTER TIMEOUT for interface en0, timeout=10.0s, reason=Assoc token=163 Sun May 22 10:45:42.056 Info: <airportd[246]> RESUME AWDL AFTER TIMEOUT for interface en0, timeout=10.0s, reason=Assoc token=164 Sun May 22 10:45:42.513 Driver Event: <airportd[246]> _bsd_80211_event_callback: SCAN_CACHE_UPDATED (en0) Sun May 22 10:45:42.539 <kernel> en0: Terminating supplicant. Sun May 22 10:45:42.539 <kernel> RSNSupplicant: Releasing authenticator for 00:00:00:00:00:00 Sun May 22 10:45:42.540 Assoc: <airportd[246]> <en0> Auto-join association timed out on network ••••• ••• , returned error code -3905 ***** Sun May 22 10:45:42.540 Info: <airportd[246]> Failed to associate to Wi-Fi network ••••• ••• on interface en0, returned error code -3905 *****

What is highly strange is that this function LSOpenURLsWithRole is marked as deprecated ending on version 10.10 ( Yosemite ) developer LSOpenURLsWithRole documentation How is it possible that the application Preview.app might use it on a version of MacOS which is the 10.13 ( High Sierra: because this is the one on which the incident is under debugging )?

[empty answer to replace the missing function: delete answer.]

I advise you to run Disk Utility in recovery mode. Thus there will be one uniq process running on your disk. It is safer and faster.

Why wouldn't you create such a folder: /Library/Application Support/application_name like this: _App_dir_name="/Library/Application Support/application_name" /usr/bin/sudo mkdir ${_App_dir_name} /usr/bin/sudo chmod 2766 ${_App_dir_name} This is the way many application are managing their globally used files. Look for example at: /Library/Application Support/Apple/Photos/Print Products

Matt: thank you. I don't need an API, there is already a very large set of great tools (pfctl, pfd, InternetSharing…), I just need a documentation. I suggested an enhancement on "security documentation".