Help please: MacBook, macOS 11.5.2 install, hang

I decided that I should install Big Sur on my MacBook (Retina, 12-inch, Early 2015) that had been running Mojave, so that it could get security updates. System Preferences > Software Update offered 11.5.2 and I told it to proceed. It appeared that the Installer finished its job and the MB was restarting, when the thermometer bar stopped at about 40% for about three hours. I disconnected it from the external display (so I could use the external display with another Mac and type this message); the internal display was completely black. The MB is now open and connected to power and I’m hoping it will come back to life.

If it doesn’t, what should I do?

Before starting the update process, I cloned the MB using CCC, which apparently completed successfully. Could I simply restart the MB, boot from the clone, and restore from the clone? (If so, please remind me how to do that. I’m frazzled.) If I do all that, should I try again? Thanks for any advice.

I have been having similar problems with my iMac for macOS 12, 12.1, 12.2 and yesterday 12.3

In all four cases AppleCare had me pull the power cord, wait a minute, plug back in and power up. My iMac then completed the install.
Apparently the code that starts the restart was sending the computer into a frozen state.

I know a MacBook doesn’t have a power cord but maybe you can try something equivalent

Good luck


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You were asked to perform an SMC reset.

If you have an Apple Silicon Mac, there is no SMC chip and therefore no corresponding procedure. For Intel Macs:

On a desktop Mac, this is done using the procedure you described.

For laptops with a T2 chip:

  • Before trying an SMC reset: Shutdown, then hold the power button down for 10 seconds. Then wait a few seconds and press the power button to turn on the Mac.
  • If that doesn’t work, press and hold CTRL, OPTION and SHIFT for 7 seconds. Then, while still holding them down, press and hold the power button for another 7 seconds. Then release all four buttons and press the power button to turn on the Mac.

For a pre-T2 laptop with non-removable batteries, the procedure is similar, but for 10 seconds.

For a laptop with a removable battery, remove the battery, hold the power button for 5 seconds, then reinstall the battery and press the power button to turn on the Mac.

(There are other procedures for older Macs, but they’re not listed on that page.)

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Thanks for the reply.

I wasn’t watching the computer, but when I returned, it appeared that the restart had occurred and then stalled. I posted here because I recall horror stories of apparently stalled computers that became unusable after the installation was interrupted.

Thanks for the instructions and especially for the pointer to the source material. I often follow the links you provide and learn even more.

It has now been over 24 hours that the screen has been blank. At this point, I assume I have nothing to lose by forcing a shutdown (if it isn’t already shut down) and restarting. If I do so, is there any downside to resetting the SMC before restarting?

Any chance this could be related to this BigSur upgrade problem from Oct 2021?

Not really. The SMC chip is responsible for managing (among other things) the power on/off state of various on-board peripherals and battery charging. It’s actually a small microcontroller running custom firmware that Apple wrote for it.

If it malfunctions or crashes, all kinds of things will fail - typically manifesting as something that won’t turn on, won’t turn off or won’t charge. The SMC reset sequence reboots it.

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Certainly the symptom matches the description, and I failed to check for the existence of such files before attempting the upgrade (because I had forgotten about the problem), but I did check at the time this problem was discussed in TidBITS and I had very few files. Maybe this weekend I’ll have time to work on this problem. (Fortunately for me, the MacBook is a secondary computer and I can get along without it.)


The problem discussed by Mr. Macintosh was later fixed by Apple in the most recent updaters/installers. I guess I’m not understanding why Software Updates offered you 11.5.2 from last August when 11.6.5 is the latest available.

That bewildered me, once I realized it. I have no answer.

I reset the SMC and restarted, and the thermometer bar under the Apple appeared to be just where it had been when everything stopped, and it hasn’t budged it 2.5 hours.

Should my next step be to restart with the clone disk attached and copy the clone back to the internal? If I want to do that, is holding option at startup the correct procedure? Or should I restore from a Time Machine backup? If I want to do that, is holding command-R at startup the correct procedure?


OP here. I believe this set of troubles is behind me.

I booted into Recovery and chose to restore from Time Machine. I assume that failed; I was immediately returned to a screen where I could choose to restore from Time Machine. The second time, I chose to have Big Sur installed. (Actually, I chose Reinstall Big Sur, which bemused me, since I had never run Big Sur on the MacBook. It was my attempt to install Big Sur, so I could get current security updates, that led to this thread.)

By the way, to boot into Recovery, one must hold down the command key and the keyboard key with an R on it. I phrase it that way because I use a keyboard layout that has the key that types R in a different location. It was after two apparent failures to boot that I thought that maybe the key combination was hard-coded because it needed to be detected before keyboard preferences were loaded. Still, since I use an Apple-provided keyboard layout, it does seem like the instructions could have been clearer.

After Big Sur was installed, there were no Admin users. In other words, all users had been changed to Standard. (Adam reported a similar situation in LittleBITS: New Year’s Resolution, macOS Upgrades, Ad Hoc Wi-Fi Networks - TidBITS. I had dutifully saved a note just in case I needed the information, and I forgot that I had saved that note. It was only when I went to save a note after I finally got the MacBook running again that I found the first note. Memory is the second thing to go.) Unlike what Adam reported in his article, I did get an authentication dialog that showed what had been an Admin user, so I was really flummoxed by the continued assertion by macOS that I had provided an incorrect password.

As noted above, when I told Software Update to install Big Sur (before starting this thread), it said it would install 11.5.2. Recovery did not tell me what version it would install, but About This Mac tells me it was 11.6.5, as one would expect.

I just looked at updating an iMac (Retina 5K, 27 inch, Late 2014) from Mojave, and Software Update offered macOS 11.5.2. Perhaps it’s showing the wrong version but would install the latest Big Sur, but I was taken aback enough that I postponed the update to ask the community for suggestions. Certainly I hope to avoid the experience I had with the MacBook. Comments?

Why not just install 11.5.2 and then see if it offers you 11.6.5?

Mainly because I’m so skittish after the horrible experience with the MacBook. Telling Software Update to install Big Sur is one option, and using Recovery to install Big Sur is another. I suppose using Software Update is the way to go, because then I have Recovery to fall back on.

I was hoping one of the gurus would say, “Probably you did X with the MacBook, and if you do Y instead with the iMac, all will be well.” (I was hoping, but not expecting.) My only guess would be to use ethernet rather than Wi-Fi (which would be a bit inconvenient), but I don’t believe that should make any difference—and if it did, I would expect Wi-Fi to be preferred.

But that does remind me that my internet went out during the installation on the MacBook (after the installer had finished downloading). Since the internet connection was down, it would have affected both Wi-Fi and ethernet, so no advantage to one over the other. But might that have caused the problem? I would have expected the installer to run on its own, but maybe it needed to contact the mothership, timed out, and that caused my difficulty. Opinion?

I don’t know that the installer needs to contact Apple while running, but I wouldn’t be entirely surprised. My general thinking about this situation is that it’s not worth stressing about. Nothing should go wrong—it’s not like there are known problems with standard upgrades. However, you should also always have at least one current full backup before you perform any significant macOS update, such that in the worst case, you can reformat the drive, reinstall macOS, and restore from backup. That’s highly unlikely to be necessary, and it’s not like you have any alternative—there’s no other way to stay current with security updates and bug fixes.

In other words, make sure your backups are up to date, wait until you have some time if things go south, and then just click the update button. There’s no win in overthinking it. :slight_smile:

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Thank you for that reality check. While in 100% of my recent upgrades, things went wrong, that statistic is based on a sample size of one.

Last time (the one time that things went wrong), I did make a clone just before trying to upgrade (and I’ll do it this time, too). I didn’t use the clone last time; I installed the upgrade from Recovery. Do you see an advantage to restoring from the clone compared to upgrading from Recovery? As far as I could tell, all my data (there was very little; it wasn’t my primary computer) survived the crash and eventual upgrade.

In the future, I do not expect to have a full clone, because I don’t expect to jump through the hoops needed to get a bootable clone of Big Sur or later. I expect to have a clone of the Data volume prior to future upgrades. Do you have any criticism of this plan? (I know there have been articles in TidBITS about bootable clones in the Big Sur and Monterey era. Many of the details went over my head at the time, because they weren’t pertinent to my situation at the time. But I came away with the impression that having a backup of data was a good compromise between effort and security, and I’m asking if I understood that correctly.)

At this point, I think it’s safest to install a new version of macOS from Recovery and then bring all your data back using Setup Assistant from your most recent backup. I like duplicates for that over Time Machine, but both will work.

Thanks, Adam. (Sorry for the slow response. Busy, busy.)

The plan now includes installing Office 365 (because a Microsoft addict uses that Mac and Office 2011 is too long in the tooth). Do you have any advice on sequence (Office then Big Sur or Big Sur then Office)?

I’d say Big Sur and then Office, because the latest release of Office 365 only supports Catalina and later, so you’ll have an update post-upgrade to Big Sur anyway.

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Thanks, Doug. I was so busy taking a victory lap about getting approval to move from Office 2011 that I hadn’t even looked at the requirements for 365.