Don’t turn off Wi-Fi in 10.9! (And how to recover a frozen Mac if you do)

Question

Level 1

54 points

Don’t turn off Wi-Fi in 10.9! (And how to recover a frozen Mac if you do)

Turning off Wi-Fi in Mavericks is causing some older (and not-so-old) Mac’s to freeze almost instantly and then again during boot, repeatedly. I’m not sure why 10.9 (build 13A603) is freezing when wi-fi is disabled, but another (really bad) defect is freezing Mavericks at boot during the initialization of the wi-fi ethernet adapter (usually interface en1) when it is disabled.

You cannot fix this problem with Safe Boot, Repair Permissions, Repair Disk, re-install Mavericks, restore from Time Machine backup, reset the SMC, reset PRAM, or boot into single-user mode. Thus far, the only solution is to boot from a (homemade) Install OS X Mavericks USB, erase the hard drive, perform a clean Mavericks install, re-install your applications, and manually restore your data. And if you innocently turn off wi-fi again, you will have to repeat this procedure. However, I have worked out an alternative solution…

The work-around is to manually enable the wi-fi Ethernet adapter in the system configuration. Specifically, the PowerEnabled setting in /Library/Preferences/SystemConfiguration/preferences.plist needs to be changed from ‘false’ to ‘true’:

<key>Interface</key>

<dict>

<dict>

<key>AirPort</key>

<dict>

<key>JoinModeFallback</key>

<array>

<string>DoNothing</string>

</array>

<key>PowerEnabled</key>

<key>RememberJoinedNetworks</key>

<true/>

<key>RequireAdminIBSS</key>

<key>RequireAdminNetworkChange</key>

<key>RequireAdminPowerToggle</key>

</dict>

This change, however, is not straightforward. In short, you need to boot from the Install OS X Mavericks USB, and edit this file in the primary volume (e.g. /Volumes/MacBook Pro HD.) You cannot perform this edit in single-user mode because it boots from primary volume, which is read-only in this case. (Perhaps the primary volume is read-write if you boot from the Recovery HD volume, but I have not tried that yet.) Once you’ve booted, open the Terminal application from the Utilities pull-down menu and change directory to /Volumes/<primary volume>/Library/Preferences/SystemConfiguration. Make a backup copy of preferences.plist, and use vi or emacs (under /Volumes/<primary volume>/usr/bin) to make the required edit. Repair Permissions afterwards to be safe and reboot normally.

I was ready to buy a new MacBook Pro during the upcoming Black Friday sales, but I am happy to leave wi-fi on until Apple fixes this #$@&*! issue and save $2500.

Questions, comments and criticism are welcomed.

Regards,

Ira

MacBook Pro, OS X Mavericks (10.9), 2007 15" Core 2 Duo 2.4GHz

Posted on Nov 26, 2013 6:50 AM

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Answer 1

Nov 26, 2013 3:07 PM in response to Ira Wolf 81

Thanks to Ira for pointing this out. My old MBP has been stuck at 10.8.4 because of this problem. It sounds like I'd be safe to upgrade that machine to 10.9 by enabling WiFi in the manner described.

As an alternative to booting from the Install OS X Mavericks USB, it would be easier (assuming that you have another Firewire-equipped Mac) to simply boot the problematic MBP in Firewire Target Mode, and then make the edit that Ira describes on the target disk.

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Answer 2

Nov 26, 2013 4:08 PM in response to Ira Wolf 81

Hi Ira!

Just wanted to point out that single user mode can mount your hard drive in read/write if you issue the command:

mount –uw /

at the command prompt.

I had the same issue with my MBP late 2007 and the WiFi, but in my case I just reinstalled Mavericks and restored the Time Machine backup and everthing worked fine.

PS: I also suggest to use "nano" to edit the file, it's easier to use than "vi".

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Answer 3

Ira Wolf 81 Author

Level 1

54 points

Nov 27, 2013 4:52 AM in response to AlfaMikeDelta

Thanks for mount hint! That make the recovery steps as simple as:

Boot into single user mode (command-option-s).
Make volume read-write (mount -uw /)
Edit /Library/Preferences/SystemConfiguration/preferences.plist to enable en1 (another user suggested deleting it.)
Reboot

I'll check into nano as I can't stand vi, but my fingers knows emacs better than my brain.

Thanks!

Ira

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Answer 4

bigd_pdx

Level 1

10 points

Nov 27, 2013 6:29 AM in response to Ira Wolf 81

Do you have any more specifcs on how this occurs? I've got a couple of Macs running Mavericks that have had wi-fi turned on and off numerous times with no ill effects. It'd be nice to know the circumstances that you've experienced this.

D

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Answer 5

Ira Wolf 81 Author

Level 1

54 points

Nov 27, 2013 8:51 AM in response to bigd_pdx

Hi D,

Simply turning off wi-fi triggers this issue.

I have a mid-2007 15" MBP 2.4 GHz Core 2 Duo (macbookpro3,1.) This issue seems to affect older MacBooks. If I were cynical, I'd say that Apple gave out Mavericks for free with the intention of selling new MacBooks to those with older ones. Regardless, their testing of Mavericks with the older "supported" devices was lacking to say the least.

Regards,

Ira

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Answer 6

Ira Wolf 81 Author

Level 1

54 points

Dec 4, 2013 7:42 AM in response to Ira Wolf 81

I have been working with some good folks in Apple Tech Support on this wi-fi issue and they were completely unaware of it. I have reproduced the issue for them and sent them a huge amount of logs gathered with their Capture Data application. I was told that Apple engineers will be reviewing them today. I'll ping them on Monday if I haven't heard back from them by then.

They also have some internal confusion about whether Mavericks is supported on mid-2007 MBPs or not. One tech initialially referenced http://en.wikipedia.org/wiki/OS_X_Mavericks, which stated that this model was not supported; However, the http://www.apple.com/osx/specs and http://support.apple.com/kb/HT5842 (Nov 6, 2013 update) webpages list them as being supported. This model is also listed as being vintage/obsolete in http://support.apple.com/kb/ht1752, which means Apple's not supporting in any way.

I'm curious if anyone else has this wi-fi issue on late-2007 models or later? Perhaps only the mid-2007 MBPs fell into this support hole...

Regards,

Ira

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Answer 7

Dec 8, 2013 11:01 AM in response to Ira Wolf 81

Ira & AlfaMikeDelta,

Thanks for the detailed posts, they really helped me out. I've also got a late 2007 Macbok Pro 3,1, and got bit by this twice.

I first had this problem a few days after the Mavericks release, and at the time could not find any clues. It was baffling, because every kind of volume repair, safe boot, etc would not help, as you know. I also did not know what the triggering event was the first time.

The second time, I saw the pattern and was able to find the posts that you had made in between my two episodes.

Ira, here is a miniscule bit of additional information that may be of interest. It seems that it is possible to turn wifi off, if you have an ethernet cable connection.

Both times I got bit, this was the pattern:

1. Plug Mac directly into cable company router, via ethernet cable, and get an IP address from the router via DHCP (I was examining an ISP problem and so wanted to eliminate as much of my own LAN gear as possible)

2. Turn off wifi (the Macbook is still ok, and has IP 10.1.10.1 on the hard line)

3. Do something with the web browser (One time, my ISP was OK. The other time, I had no connectivity, but of course still had an IP address from the router)

4. Unplug ethernet cable--immediate freeze, failure to reboot

So, in my case, having a properly assigned IP address from DHCP kept me safe. As soon as both wired and wireless had no assigned IP, the trouble started. Not sure that is meaningful, but that's what I saw.

Thanks again fellas, this thread saved me hours of time and a lot of confusion.

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Answer 8

Ira Wolf 81 Author

Level 1

54 points

Dec 9, 2013 8:47 AM in response to Lost Carcosa

Hello Lost Carcosa,

I'm glad this information helped someone else.

I think you could be on track for identifying the root cause to be within DHCP address assignment. Keeping wi-fi enabled merely prevents the freeze issue from occurring.

This issue manifests itself when turning off wi-fi and when booting. I have seen the freeze occur up to a minute after turning off wi-fi. I don't there are two separate defects; just one defect with two ways of tiggering it.

Hmm, the DHCP developer within me is now thinking about monitoring DHCP packets with WireShark while messing with the DHCP client settings. I wonder what Mavericks will do if I generate a DHCP Terminate request from my DHCP server (a FIOS router/AP from ActionTec) while not having a wired connection...

Regards,

Ira

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Answer 9

Ira Wolf 81 Author

Level 1

54 points

Dec 10, 2013 9:39 PM in response to Ira Wolf 81

I tried disabling DHCP from both the client and server sides as best I could, but was unable to reproduce the freeze that occurrs when disabling Wi-Fi. Given that this issue is seen primarily on older MacBooks, I suspect it to be an Wi-Fi/Ethernet driver issue.

As for Apple support, they're still awaiting to hear back from the Apple engineers...

Regards,

Ira

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Answer 10

Dec 11, 2013 10:46 AM in response to Ira Wolf 81

If you have another Mac around, you can start the frozen Mac in Firewire target mode. Connect Firewire cable, boot holding the T key.

Then open /Library/Preferences/SystemConfiguration/preferences.plist in frozen Mac.

with Text Edit

and replace, as Ira wrote, false with true.

<key>PowerEnabled</key>

Miguel

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Answer 11

Dec 11, 2013 10:57 AM in response to Ira Wolf 81

I tried disabling DHCP from both the client and server sides as best I could, but was unable to reproduce the freeze that occurrs when disabling Wi-Fi. Given that this issue is seen primarily on older MacBooks, I suspect it to be an Wi-Fi/Ethernet driver issue.

I bet you're right. Thanks for the update.

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Answer 12

Aedant

Level 1

10 points

Dec 17, 2013 1:34 PM in response to Ira Wolf 81

Hi everyone!

Just to add some more information, I have a late 2009 27in iMac AND I HAVE THIS ISSUE TOO!!! It freezes instantly when I turn the wi-fi off. Also, sometimes when I reboot after that, my usb Keyboard will not be detected until I reboot a second time. I don't know if this issue is related. I only became aware of it last week, and I was panicking because I thought my hard drive was starting to fail. But now I'm seeing I'm not the only one with this problem, so I'm weirdly happy.

If there's anything I can do to help, provide a log or something, just tell me what to do!

Francis

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Answer 13

Ira Wolf 81 Author

Level 1

54 points

Dec 17, 2013 9:59 AM in response to Ira Wolf 81

I just updated to 10.9.1 and it does NOT fix this Wi-Fi issue. I turned off Wi-Fi and my system froze a minute later.

Sorry folks,

Ira

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Answer 14

etresoft

Level 9

51,022 points

Dec 17, 2013 10:07 AM in response to Ira Wolf 81

What is this WiFi issue of which you speak? It sounds like you are thinking that some sort of system modification or misconfiguration is a problem with Mavericks. I suggest reviewing what changes you made and undoing them.

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Answer 15

Ira Wolf 81 Author

Level 1

54 points

Dec 17, 2013 10:25 AM in response to etresoft

Hello Etresoft,

First, thanks for the etrecheck tool; it really helped identify legacy items that needed removal. However, in the end I wiped my drive clean with a 3-pass erase and installed Mavericks from scratch. At that point, simply turning off Wi-Fi in my 2007 MBP 15" Core 2 Duo 2.4GHz caused the system to freeze and prevented it from booting. There is nothing available to undo. The work-around is described in my 11/27/13 response above. BTW Apple Tech Support is still awaiting an Apple Engineering response.

Regards,

Ira

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