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Two iMacs will not boot after the 10.11.4 update.

Two iMacs will not boot after the 10.11.4 update. Progress bar starts to move then text appears on the black screen saying unexpected sigkill of launchd. It then gets stuck in a loop of trying to boot. Tried resetting SMC and PRAM. No success. Booted into recovery mode and ran disk utility. Drives reported OK. Chose to reinstall OS X from the recovery mode option list (presume this would be 10.11.4). Install completed but again fails to boot. Reinstalled 10.11.0 successfully from a USB stick and downloaded the 10.11.4 combo updater. The installation appears to work but again the macs will not boot. Same "unexpected sigkill of launchd" error. One mac is now back working properly with 10.11.3 the other will be shortly. Is there a problem with the updaters? Our IT support use Munki to push out updates overnight. Thankfully we were able to stop this before the other 20 or so macs had the same problem.

iMac, OS X El Capitan (10.11.3)

Posted on Mar 22, 2016 8:44 AM

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40 replies

Mar 22, 2016 9:40 AM in response to Martin Montgomery

Please read this whole message before doing anything.

This procedure is a diagnostic test. It’s unlikely to solve your problem. Don’t be disappointed when you find that nothing has changed after you complete it.

The purpose of the test is to determine whether the problem is caused by third-party software that loads automatically at startup or login, by a peripheral device, by a font conflict, or by corruption of the file system or of certain system caches.

Disconnect all wired peripherals except those needed for the test, and remove all aftermarket expansion cards, if applicable. Start up in safe mode and log in to the account with the problem.

Note: If FileVault is enabled in OS X 10.9 or earlier, or if a firmware password is set, or if the startup volume is a software RAID, you can’t do this. Ask for further instructions.

Safe mode is much slower to start up and run than normal, with limited graphics performance, and some things won’t work at all, including sound output and Wi-Fi on certain models. The next normal startup may also be somewhat slow.

The login screen appears even if you usually login automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.

Test while in safe mode. Same problem?

After testing, restart as usual (not in safe mode) and verify that you still have the problem. Post the results of the test.

Mar 22, 2016 9:56 AM in response to Martin Montgomery

If you don't already have a current backup, please back up all data, then reinstall the OS.* You don't need to erase the startup volume, and you won't need the backup unless something goes wrong. If the system was upgraded from an older version of OS X, you may need the Apple ID and password you used.

There are ways to back up a computer that isn't fully functional. Ask if you need guidance.

If you installed the Java runtime distributed by Apple and still need it, you'll have to reinstall it. The same goes for Xcode. All other data will be preserved.

*The linked support article refers to OS X 10.11 ("El Capitan"), but the procedure is the same for OS X 10.7 ("Lion") and later.

Mar 22, 2016 10:07 AM in response to Linc Davis

As stated in original post, I tried to reinstall the OS via the recovery mode. This installed "successfully" but would not boot, same error with launchd. We then used a usb stick to roll back to 10.11.0. This worked and the mac booted successfully. Logged in as the main user (admin) and tried to install the 10.11.4 combo updater. This installed "successfully" but on restart it kernel panicked with the same launchd error. This mac was then restored from backup to 10.11.3. The other mac was rolled back to 10.11.0 with the USB stick and then updated to 10.11.3 using the 10.11.3 combo. Both macs are now booting and functioning properly having been rolled back to 10.11.3.

Mar 22, 2016 10:11 AM in response to Martin Montgomery

1. This procedure is a diagnostic test. It changes nothing, for better or worse, and therefore will not, in itself, solve the problem. But with the aid of the test results, the solution may take a few minutes, instead of hours or days.

The test works on OS X 10.8 ("Mountain Lion") and later. I don't recommend running it on older versions of OS X. It will do no harm, but it won't do much good either.

Don't be put off by the complexity of these instructions. The process is much less complicated than the description. You do harder tasks with the computer all the time.

2. If you don't already have a current backup, please back up all data before doing anything else. The backup is necessary on general principle, not because of anything in the test procedure. Backup is always a must, and when you're having any kind of trouble with the computer, you may be at higher than usual risk of losing data, whether you follow these instructions or not.

There are ways to back up a computer that isn't fully functional. Ask if you need guidance.

3. Below are instructions to run a UNIX shell script, a type of program. As I wrote above, it changes nothing. It doesn't send or receive any data on the network. All it does is to generate a human-readable report on the state of the computer. That report goes nowhere unless you choose to share it. If you prefer, you can act on it yourself without disclosing the contents to me or anyone else.

You should be wondering whether you can believe me, and whether it's safe to run a program at the behest of a stranger. In general, no, it's not safe and I don't encourage it.

In this case, however, there are ways for you to decide whether the program is safe without having to trust me. First, you can read it. Unlike an application that you download and click to run, it's transparent, so anyone who understands the code can verify what it does.

You may not be able to understand the script yourself. But variations of it have been posted on this website many times over a period of years. Any one of the millions of registered users could have read the script and raised the alarm if it was harmful. Then I would not be here now and you would not be reading this message. See, for example, this discussion.

Nevertheless, if you can't satisfy yourself that these instructions are safe, don't follow them. Ask for other options.

4. Here's a general summary of what you need to do, if you choose to proceed:

☞ Copy the text of a particular web page (not this one) to the Clipboard.

☞ Paste into the window of another application.

☞ Wait for the test to run. It usually takes a few minutes.

☞ Paste the results, which will have been copied automatically, back into a reply on this page.

These are not specific instructions; just an overview. The details are in parts 7 and 8 of this comment. The sequence is: copy, paste, wait, paste again. You don't need to copy a second time.

5. Try to test under conditions that reproduce the problem, as far as possible. For example, if the computer is intermittently slow, run the test during a slowdown.

You may have started up in safe mode. If the system is now in safe mode and works well enough in normal mode to run the test, restart as usual before running it. If you can only test in safe mode, do that.

6. If you have more than one user, and only one user is affected by the problem,, and the affected user is not an administrator, then please run the test twice: once while logged in as the affected user, and once as an administrator. The results may be different. The user that is created automatically on a new computer when you start it for the first time is an administrator. If you can't log in as an administrator, test as the affected user. Most personal Macs have only one user, and in that case this section doesn’t apply. Don't log in as root.

7. Load this linked web page (on the website "Pastebin.") Press the key combination command-A to select all the text, then copy it to the Clipboard by pressing command-C.

8. Launch the built-in Terminal application in any one of the following ways:

☞ Enter the first few letters of its name ("Terminal") into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ Open LaunchPad and start typing the name.

Click anywhere in the Terminal window to activate it. Paste from the Clipboard into the window by pressing command-V, then press return. The text you pasted should vanish immediately.

9. If you're logged in as an administrator, you'll be prompted for your login password. Nothing will be displayed when you type it. You will not see the usual dots in place of typed characters. Make sure caps lock is off. Type carefully and then press return. You may get a one-time warning to be careful. If you make three failed attempts to enter the password, the test will run anyway, but it will produce less information. If you don't know the password, or if you prefer not to enter it, just press return three times at the password prompt. Again, the script will still run.

If the test is taking much longer than usual to run because the computer is very slow, you might be prompted for your password a second time. The authorization that you grant by entering it expires automatically after five minutes.

If you're not logged in as an administrator, you won't be prompted for a password. The test will still run. It just won't do anything that requires administrator privileges.

10. The test may take a few minutes to run, depending on how many files you have and the speed of the computer. A computer that's abnormally slow may take longer to run the test. While it's running, a series of lines will appear in the Terminal window like this:

Test started

Part 1 of 4 done at: … sec

Part 4 of 4 done at: … sec

The test results are on the Clipboard.

Please close this window.

The intervals between parts won't be exactly equal, but they give a rough indication of progress.

Wait for the final message "Please close this window" to appear—again, usually within a few minutes. If you don't see that message within about 30 minutes, the test probably won't complete in a reasonable time. In that case, press the key combination control-C or command-period to stop it. Then go to the next step. You'll have incomplete results, but still something.

In order to get results, the test must either be allowed to complete or else manually stopped as above. If you close the Terminal window while the test is still running, the partial results won't be saved.

11. When the test is complete, or if you stopped it manually, quit Terminal. The results will have been saved to the Clipboard automatically. They are not shown in the Terminal window. Please don't copy anything from there. All you have to do is start a reply to this comment and then paste by pressing command-V again.

At the top of the results, there will be a line that begins with the words "Start time." If you don't see that, but instead see a mass of gibberish, you didn't wait for the "close this window" message. Please wait for it and try again.

If any private information, such as your name or email address, appears in the results, anonymize it before posting. Usually that won't be necessary.

12. When you post the results, you might see an error message on the web page: "You have included content in your post that is not permitted," or "The message contains invalid characters." That's a bug in the software that runs this website. Please post the test results on Pastebin, then post a link here to the page you created.

If you have an account on Pastebin, please don't select Private from the Paste Exposure menu on the page, because then no one but you will be able to see it.

13. When you're done with the test, it's gone. There is nothing to uninstall or clean up.

14. This is a public forum, and others may give you advice based on the results of the test. They speak for themselves, not for me. The test itself is harmless, but whatever else you do may not be. For others who choose to run it, I don't recommend that you post the test results on this website unless I asked you to.

15. The linked UNIX shell script bears a notice of copyright. Readers of ASC may copy it for their own personal use. Neither the whole nor any part may be redistributed.

Mar 22, 2016 12:26 PM in response to Linc Davis

Hi Linc,

I started that test after restoring to 10.11.3 but I had to cancel the test as it was taking more than 25 mins. We also had a response from another forum asking if we had SUIDGuardNG.kext installed.

We found that file on both restored iMacs but not on the test iMac that was successfully updated to 10.11.4 (It hadn't ever had 10.10 installed and so hadn't had the SUIDGuardNG.kext installed). I removed the kext file from one of the restored iMacs and then ran the 10.11.4 combo updater. It installed perfectly this time.


Check in /Library/Extensions.


Thanks for your help and hopefully this will solve the issue for others.

Mar 22, 2016 2:54 PM in response to Martin Montgomery

I've got a similar issue to this. Mac Pro 2012 updated to 10.11.4 and it wouldn't boot afterwards. Progress bar would get to 50% - 75% and then go no further in an hour. I disconnected second display and speakers (only other peripherals) and no change. Disk Utility in Recovery Mode didn't find anything. Safe mode wouldn't boot and the fsck -fy command (whatever that's supposed to do) didn't change anything.


I've gone back to 10.11.3 courtesy of a Time Machine restore.


Any tips?

Two iMacs will not boot after the 10.11.4 update.

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