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Month 13 is out of bounds

And obviously, it would be, because there is no month 13. But if you're unlucky enough to be a Mac user in the month of December, 2017, then you'll probably be seeing a lot of "Month 13 is out of bounds" messages in your Console. And by 'a lot,' I mean an exceedingly excessive never-ending stream of spewage…

Thousands and thousands and thousands of them—I'm getting anywhere from two to 20 per second, continuously. Ugh.

This just started happening this morning, and it's happening on all my Macs. I found one Apple developer forum thread that talks about the problem, and user Helge seems to point to a bug in mdworker

Nov 29, 2017 2:08 AM
(in response to Macho Man Randy Savage)
Nothing wrong with you code. the mdworker process is encountering an error.

01. fehler  
02. 11:04:18.125428 +0100  
03. mdworker  
04. Month 13 is out of bounds

This bug must be new with High Sierra (or we would have seen this last December, too). On top of the recent root-no-password security issue and the need to fix file sharing after that fix and a possible ssh exploit (since patched, it appears), as well as all the other glitches, High Sierra is starting to feel like someone really was high when they said "ship it!"

And sorry to be so negative about these issues, but I rely on my Macs and macOS for my work. I expect them to work, and to work well. For years, they did just that. But recently, the downward trend in the quality of the software cannot be ignored: It's a huge problem, especially when functional macOS app bugs and macOS system-level bugs that affect third party apps (both of those are roughly two years old!) aren't even responded to by Apple.

Please, Apple, for next year, give macOS zero new features and focus on quality and stability. Pretty please?

57 thoughts on “Month 13 is out of bounds”

  1. My 2014 Mac Mini is still running Yosemite, and an experimental SSD is running Sierra, noth with no problems. High Sierra looks like a ten-foot-poler.

  2. I don't believe it is just mdworker. If you look at the logs from an Apple Watch you will see the same errors. I just checked and it shows up on an iPhone as well. It is coming from calaccessd.

    1. I honestly don't know where it's coming from–there are no cal references on the Mac, just on the phone. Whatever it is, it's annoying as heck.


    1. Riccardo Ettore

      So did I, for sure, several weeks ago, in the xcode console first and then the Console app. I was wondering why the were so few results in google searches.

  3. My family desktop Mac's internal harddrive is running awfully these days, fatally crashing on a regular basis. We got a new computer, and the crashing still happened on that one. I hope this stuff gets sorted out sooner versus later, though it's already been over a month.

  4. I'm getting this and it is causing UserEventAgent to consume all my cpu and RAM. Only solution is to set the date back until November. It started after I rebooted yesterday. Something about the reboot must trigger reading of some plist or something and the cycle begins...

    1. Traced the out of control UserEventAgent to a launchd plist that uses the StartCalendarInterval key for scheduling. Unloaded the job and my computer is back to normal. Still getting loads of 'Month 13' messages in the console, but at least my computer is usable. Anyone having UserEventAgent interactions with this date bug might want to look in their LaunchAgent folders.

      1. Wow, nice detective work! Was it a launchd item you created, or one from an app? If an app, can you share the name in case others are looking for the same solution?


        1. One that I had created to run a simple shell script at the beginning of each month. But StartCalendarInterval is a valid key to use in launchd plists, and now that cron isn't really supported, this is the official way to access this functionality.

          I don't have any specific apps to look out for, but any app that makes a plist for scheduled activity and lets you schedule by calendar days might be suspect. SuperDuper might do it, etc.

          Easiest thing to do is to check /Library/LaunchAgent and ~/Library/LaunchAgent and run grep -i StartCalendarInterval * in those two directories.

          1. Hi Tim,

            I found this in the Oracle agent but this is like an 'infection' or 'cancer'. It had already spread to other processes and daemons: Bluetoothd, loginwindow, securityd, mdworker, System Preferences, com.appl.preference.datetime.remoteservice, routined,, mds, prl_vm_app (I checked this launch agent, it doesn't have it),

            launcheservicesd AH! ... oh... seriously? isn't this the process that runs under launchd to spawn pretty much everything on the mac in 'user space'?

    1. I haven't seen any crashes here, but it seems it was crashing iPhones (assuming it was the same bug). Try looking in Console and scroll back to the time of the reboot, and see if there's anything that may explain what went "boom."


    2. I'm getting crashes and restarts from it. No longer crashes if I change the date back to November.

    1. "Used a MacBook on a VMWare emulator for Xcode development".... MacBook & Xcode are Apple-only... how does that work?

      1. Google Hackintosh.

        But it sucks for anything else but occasional use (in a VM; on a bare metal, I've never tried).

        In any case, confirmation over here, same issues. The message is thrown by DragThing, BetterTouchTool, SystemEvents, CalendarAgent, and probably a bunch of others - and hundreds of times per second.

        Have opened an Apple Bug Report, as if that had ever helped.

  5. I'd like to add: Dear Apple, I don't need an ultra-slim MacBook Pro with an ultra-slim battery pack that has only 3 hours capacity when running programs that use the CPU. That's what the Macbook Air is for, isn't it?
    I'd like a Macbook Pro with an option to upgrade the hard disk drive and memory, all available ports and the good old MagSafe adapter. I don't give a f*#& about Siri and Photo editing features and I don't want to save disk space by uploading all my private files to iCloud.

    1. I've been saying that since the new Airs were introduced, and that's before the insane keyboard issues started snowballing. What the hell were they thinking soldering drives to the motherboard? RAM is bad enough but relatively reliable.

  6. I spent quite a while trying to solve this problem at the beginning of November, so it's not a December thing. I couldn't figure out the solution anyway!

    1. I wonder if it's triggered by something tickling a calendar for January or something - it definitely showed up in December for me. Odd.


  7. For me it happens in XCode, running app in simulator at this line:
    BOOL ok = [self.userLocationDictHistory writeToFile:self.userLocationDictHistoryPath atomically:YES];

  8. On Dec. 2nd I noticed new files I created had a file creation date set in 2014. I was fully updated at the time. New MacBook Pro, no touch bar.

    1. Setting the clock back to pre-December-1st is the only one I've seen…that, and wait for Jan 1st 2018, when I'm pretty sure this problem will vanish (until December 2018). Given the expected "self fixing" nature of this issue, I don't expect Apple to patch this one in High Sierra…I just hope they patch it in the 2018 release.


      1. Changing the date will cause havoc with certs, etc. as they will appear invalid due to the time shift. Maybe we'll get the update circus on macOS that iOS just went thru.

  9. My MacBook Pro was rinsed by UserEventAgent. Took full use of CPU and memory. I had to force quit it within Activity Monitor every ten minutes to keep laptop running. Thanks to this post I have just changed date to 5th November 2017 and it has stopped!!! Goodness knows whats causing it. Hopefully someone far more capable than myself will find out the cause. I am running 10.3.1

  10. Hi!
    To override the havoc with certs, set the date to January 1st. Does the sam trick than setting the date to November.

  11. Same for me, I came here after having google EventUserAgent + memory leak. High Sierra is a mess. I have been on osx for 1 year and half after 5 year of debian and averall I have to say nothing beat osx in term of ergonomy, considering all desktop improvement avaible. I'm very happy with my macbook 12, decent power you can bring with you on the way without breaking your shoulder.

    But in matter of stability, osx is simply a shame. I could stay litterally months without shuting down my last laptop on debian, always hibernating for travel. You could throw a debian computer by the windows, the os would still run smoothly after reaching the ground. With osx, I can't one week since high sierra. Often I have to restart several time a week because osx doesn't respond anymore. It just reached new low. Never the folks behind debian would dare launch such a poor release

  12. I shall point out here that in the Simpsons they refer to the 13th Hour of the 13th Day of the 13th Month… it’s named Smarch, and I think it’s an apt name for this issue.

  13. Pierre Castera

    OS 10.13.2 fixed the problem with max memory usage. I can still see the error message Month 13 is out of bounds, but it does not slow down my iMac.

  14. 'Month 13 is out of bounds' is the result of calling Deprecated NSDate procedure 'descriptionWithCalendarFormat' a formerly useful routine also still apparently used extensively by OS10.13.2.

    Go figure

  15. Well, now I know what is "think different!". :)) JUNEBRUARY - 13-th month in Apple's kingdom! :))
    Cannot believe they have so stupid developer team!

  16. I'm not yet on High Sierra. I still run Sierra 10.12.6.

    I'm seeing the "Month 13 is out of bounds" error inside Xcode9.0.1 when I have the environment var set: CFNETWORKING=1

  17. In my situation this was not caused by OSX but a 3rd party application. If you open the console app and look at the messages there is a column that tells you which process is causing the problem. I killed the app and no longer get those errors.

    1. Suz:

      These messages are caused by any application—third party or otherwise—that calls the the deprecated NSDate procedure, as explained above by "Mike." Yes, you can see which app(s) are causing the problem in Console, but they are not just third-party apps.

      As of today, for example, I see Twitter and BetterTouchTool throwing the error. So yes, I could quit those...but I also see Dashboard Client, loginwindow, AOUMonitor, and UserEventAgent throwing the error. Not much I can do about them, as they're core macOS technologies used by Apple.

      The good news is that this appears to be fixed in the latest macOS 10.13.3 beta, at least based on my limited testing.


  18. I'm getting about 20 of the errors a second still. Doesn't affect anything, (from what i can tell). 10.13.2 has stopped it from slowing down my MacBook. Maybe we'll never see the error disappear.

  19. After working with Apple escalation, they claim that 10.13.3 fixes this. I can't test since the problem vanished for me in the first week of January. If anyone is still having the problem, try 10.13.3 and report back.

    1. It's definitely gone here. I saw a few earlier today (pre upgrade) from iTunes, but none since I installed it.


        1. Zeeshaan Aamir

          After updating 10.13.3 still i am getting the same problem ..Did your problem solved

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