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Mac OS X 10.3.x: Kernel panics upon location change

Mac OS X 10.3.x: Kernel panics upon location change

Published Thursday, Feb. 26th

The past few days we've been covering reports of kernel panics on PowerBooks and iBooks when switching Network Locations. Yesterday we summarized the main factors that appeared to be involved in this issue after a few days of reader reports. Since then, we've received even more reports of this issue from readers; in fact, whereas yesterday we noted that all reports appeared to point to PowerBooks and iBooks running Mac OS X 10.3.2, after another day of reports it also appears we can add AirPort 3.3 as a common factor.

Switching to Ethernet a contributing factor? After combing through the myriad reports, it also appears that the most common situation involves switching to an Ethernet connection. One reader's response is typical:

"Yesterday morning I needed to make a faster transfer than AirPort will afford, so I plugged the Ethernet cable for my 10/100 switch into my PowerBook and switched from an AirPort-only to an Ethernet only [Location]. I immediately kernel panicked. It's the only time I've had that happen."

We've also had a good number of readers emphasize that it occurs mainly when switching to an Ethernet connection with a static IP address. Reader Ed Dyer writes:

"Definitely began after Airport 3.3 and/or 10.3.2 (from 10.3.1) update. Have not yet installed iSync 1.4 or iChat 2.1 beta. I usually experience it when swtiching from a DHCP connection to a static IP. I can't confirm whether or not I had cables plugged in, but this happened even when my switch was from an ethernet to ethernet situation, though airport WAS turned on. I definitely fit the 'wake from sleep and immediately change location' profile."

Having Ethernet cable plugged in before switching locations/booting? A significant majority of readers who've written in about this issue report that the issue only seems to occur when the Ethernet cable used to connect to a network is plugged in when switching Locations or booting. For example, Andy Kurtz reports that it occurs with a cable connected when he boots up:

"When I go from using Airport at home to using wired Ethernet at school, the first time I boot my PowerBook G4 Titanium and the Ethernet cable is plugged in I get the [kernel panic screen]. If I boot with the Ethernet cable unplugged it boots fine then I can plug in the cable and Ethernet works. I assume that the system is changing locations automatically which is causing the crash."

David Kinderlehrer notes that his experiences mirror those of Kay Mathiesen, quoted yesterday: switching while having the Ethernet cable plugged in causes the panic, whereas unplugging the cable before switching does not lead to a panic.

Finally, reader Ivan Trundle provided a comprehensive report that appears to mesh with the above theories; below are a few key excerpts:

"I get the gray screen of death every morning when I take my 1.33GHz G4 17" laptop [OS X 10.3.2] to work [Ethernet, various IP addresses] from home [AirPort]. My network preferences are set to use ethernet over airport, so in theory I should be able to simply plug in the ethernet cable and go. Since updating the Airport software to v3.3, I get kernel panics as follows:

"At work, before opening the laptop, I plug in the ethernet cable (as I have always done prior to AirPort upgrade) and open lid. Now I get a kernel panic every time. Upon safe reboot, I always find an orphaned indirect node under fsck, and then reboot once more to get back to normal. Once fired up, the machine correctly identifies the network via Ethernet."

Location change not necessary? Yesterday we noted that it appears that a change in network interface -- for example, AirPort to Ethernet -- appears to precipitate the problem. It's actually possible for Mac OS X to change network interfaces without actually changing Network Locations. In fact, that's what the default "Automatic" Location does: It uses the first interface listed if it can connect successfully; if not, it uses the next interface, and so on. Reader Melvyn Goldstein reports that he doesn't even have to change Network Locations for a kernel panic to occur:

"Usually I leave my PB Location on 'Automatic' ... when I'm at home it uses an Airport connection to COMCAST, when I'm at my office, I use an Ethernet cable to connect to our LAN. Several times, now, I've found that simply putting my PB to sleep at home and awakening it later in the office initiates a panic. I've not (yet) experienced any problem going the other way (office to home)."

Jeffrey Chajes notes the same scenario:

"I have had repeated problems with exactly the kinds of kernel panics you report: waking from sleep, esp. with ethernet cable attached; and even booting up with the cable attached. At this point I am NOT changing locations, but simply keeping my settings for the ethernet connection at work at all times; when I go home, the airport network automatically goes into effect. If I come to work the next morning with a sleeping Powerbook, insert the ethernet cable, and wake it up - YOU MUST RESTART YOUR COMPUTER in 4 languages appears on my darkened screen."

Although these reports may be coincidental, the fact that OS X automatically connects to the first available network type means that this problem could be related and that the real problem isn't necessarily a Location switch, but rather a change in network interface that causes the kernel panic.

Security Update fixes the problem? Yesterday we noted that reader Aaron Ciesar had success in fixing the problem by installing the recent Security Update 2003-02-23. Aaron followed up after doing more testing and confirmed that, for him, installing the Security Update stopped these kernel panics from occurring. However, other readers have reported that the problem still occurs for them after installing the Update.

Summary of factors? Based on the reports we've seen, it now appears that we can narrow down the list of contributing factors to the following:

  • PowerBook or iBook with AirPort card installed
  • Mac OS X 10.3.2
  • AirPort 3.3
  • Switching network interfaces from any interface to an Ethernet connection -- either by manually changing Network Locations or by using a Network Location with multiple interfaces (since OS X will automatically check each interface until it finds an active one) -- while an Ethernet cable is connected to the PowerBook or iBook. This includes starting the laptop up, since OS X attempts to automatically find the appropriate network interface at startup.
  • [Possibly] Waking from sleep; however, many users report that the issue occurs at startup, as well, and waking from sleep causes OS X to poll the various active network interfaces, so this could be entirely coincidental.
  • [Possibly] Switch to a static IP address; however, not all users reporting the kernel panic issue have reported using a static IP address.

Can you confirm our list of factors? Disprove it? Drop us an email at

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