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I'm seeing an error every 30 seconds in the system log, using the Console app, complaining about MirrorDisplays service only running for 0 seconds.

Nov  5 22:45:22 computer com.apple.xpc.launchd[1] (com.apple.preference.displays.MirrorDisplays): Service only ran for 0 seconds. Pushing respawn out by 10 seconds.
Nov  5 22:45:52 --- last message repeated 2 times ---
Nov  5 22:45:52 computer com.apple.xpc.launchd[1] (com.apple.preference.displays.MirrorDisplays): Service only ran for 0 seconds. Pushing respawn out by 10 seconds.
Nov  5 22:46:22 --- last message repeated 2 times ---
Nov  5 22:46:22 computer com.apple.xpc.launchd[1] (com.apple.preference.displays.MirrorDisplays): Service only ran for 0 seconds. Pushing respawn out by 10 seconds.
Nov  5 22:46:52 --- last message repeated 2 times ---
Nov  5 22:46:52 computer com.apple.xpc.launchd[1] (com.apple.preference.displays.MirrorDisplays): Service only ran for 0 seconds. Pushing respawn out by 10 seconds.

It doesn't matter if I have no external display or use an external display at the same time. How do I turn off this repeated error in the logs?

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  • I'm using macOS High Sierra v10.13.1, and this is happening to me, too. (1 external 4K TV with the lid down) – Martin Romañuk Nov 8 '17 at 13:33
  • I checked the answer from @dattwood with success and touching nothing else. – dan Aug 7 '20 at 17:15
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I had the same log complaints. They are the result of macOS detecting the secondary HDMI display and some code quality issue.

Uncheck "System Preference > Display > Show mirroring options in the menu bar when available." After reboot the log output will be gone.

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    Unchecking "Show mirroring options..." didn't work for me. The messages started showing up right after I rebooted. – Jistanidiot Mar 8 '18 at 17:56
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    Can confirm - that’s not it. – Ranza Jul 2 '18 at 16:12
  • I have a hunch that AirPlay is implicated in some way. I get this error (and the powerchime one) on my old MacBook Pro 2010 (no AirPlay Mirroring support) If I try and enable "Show Mirroring Options..." in the Display preferences panel, I see the menu bar item briefly appear and crash out. – jrg Mar 13 '19 at 22:28
  • I had the same useless Agent running, and repeated error messages without any external display. I think you fixed your problem with another System Preferences change and the next session restart. The session restart didn't restart the useless Agent. Look at the answer from @dattwood which I checked with success. – dan Aug 7 '20 at 17:13
  • @Jistanidiot: rather try this better answer apple.stackexchange.com/a/340082/22003 . – dan Aug 8 '20 at 16:29
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Unchecking "Displays have separate Spaces" in System Preferences > Mission Control and restarting the actual session will stop this useless error messages and useless Agent.

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  • It's not checked on my system and still I have the message... – Pierre Lagarde Oct 5 '20 at 11:06
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I was able to resolve this problem on my system by modifying the LaunchAgent file to only load in the LoginWindow.

In addition to eliminating the errors every 30 seconds in the log, it also appears to also have resolved an issue where my display would not turn off, regardless of the setting in Energy Saver. So, I'm pretty happy.

The steps I took were as follows:

  1. Disable System Integrity Protection so you can edit the .plist file. Do this by rebooting into the recovery partition with cmd-R, open Terminal from the Utilities menu, and type:

    csrutil disable

  2. Reboot into yoru system, then edit the .plist file with this command:

    sudo vi /System/Library/LaunchAgents/com.apple.preference.displays.MirrorDisplays.plist

  3. Comment out the line that causes the MirrorDisplays tool to load. Change this line:

          <string>Aqua</string>

    to this:

    <!--  <string>Aqua</string>   -->

  4. Then, reboot and reenable System Integrity Protection using the recovery partition as described above and type:

    csrutil enable

  5. Reboot and enjoy a clean log file!

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  • Thanks, but this didn't work for me. It still launches and the machine crashes regularly on a vanilla 10.13.5 with just FileMaker Server and TeamViewer installed. I suspect the repeated launching has something to do with receiving a TeamViewer connection, but have not investigated it deeply. I "fixed" it by renaming the executable MirrorDisplays to something else so it cannot be launched. Not sure what other effect this may have elsewhere, but as this is a server, I don't care about the display features. – AndreasT Jun 18 '18 at 6:49
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    @AndreasT: Editing com.apple.preference.displays.MirrorDisplays.plist to comment out the Aqua string, as described above, prevents the MirrorDisplays executable from being invoked while the Mac has a user logged into an interactive session. It may be that, for your purposes with an unattended server, you need to also comment out the LoginWindow string on the preceding line, which should have the same effect when the Mac has no one logged in interactively. Let me know if this works! – jdmc Sep 11 '18 at 19:04
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    No, do not tell people to "csrutil disable" without a dire warning. – ruief Oct 14 '18 at 22:12
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    Ruief, all this paranoia about "csrutil disable" is childish alarmism. We all ran our Apple computers without csrutil. Csrutil is useful to prevent newbies and iPhone users from easily being hacked. It's also very useful to lock Mac users out from being able to administer our own computers and turn us into iPhone users. Dire warnings is pointlessly alarmist language. AskDifferent and SuperUser are not nursery school. – Foliovision May 3 '19 at 7:51
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    @Foliovision : 👏🏻! 2 reboots for any admin modification. For me half an hour of wasted time and work in progress killed. – dan Jul 29 '20 at 15:06
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Editing the plist file as explained in Carl Hewitt's answer caused windows that extended across two monitors to only show on one of the two screens. The other portion of the window simply disappeared.

The following resolved the issue for me: Launch System Preferences, select Displays and uncheck "Show mirroring options in the menu bar when available."

System: 2017 27" iMac High Sierra 10.13.6 with two additional 27" ASUS displays connected via HDMI at the display. Credit to Allan & Bath Thank you.

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  • I have that preference unchecked yet I see the error message – odysseus Sep 11 '18 at 15:18
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    Re: "caused windows that extended across two monitors to only show on one of the two screens. The other portion of the window simply disappeared." — This is the normal expected behavior if the "Displays have separate Spaces" option is checked (enabled) in System Preferences > Mission Control. Is yours checked? If so, uncheck it, and then reboot (or at least log out and in again). Then all displays will be treated as a single extended desktop area, with windows free to straddle different screens. However, the menu bar and Dock will appear only on the main display, rather than all displays. – jdmc Sep 11 '18 at 19:16
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A different approach is to filter out the unwanted message from the logs.

Add the following line to /etc/asl.conf after the line starting > system.log:

? [= Sender com.apple.xpc.launchd] [= RefProc com.apple.preference.displays.MirrorDisplays] ignore

This filter can be further narrowed if desired (see man asl.conf).

Run sudo pkill -HUP syslogd to get syslogd to reload asl.conf

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  • As none of the above really works (as we can see in several comments), and changing a display management process/preference may have unknown or undesirable side effects for some... all that plus the fact there is no real problem behind this message, I think you really gave the best option : avoiding useless writes in the syslog file. – Pierre Lagarde Oct 5 '20 at 11:06

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