Can you help me update OS X?
October 12, 2015 11:06 AM   Subscribe

My Mac is (and has been) prompting me to update software. Every time we get past the "Agree" or "disagree" prompt, the window tells me it can't be installed on "Macintosh HD." There is 300-some GB of space. Any ideas what's going on?

I've just been using the old OS but now I have a situation in which I need the latest version. Any suggestions on what to do?
posted by pipti to Computers & Internet (17 answers total) 1 user marked this as a favorite
 
Can you give us some more information? Model of Mac, how old it is and the version of the OS you're trying to upgrade from?
posted by nathan_teske at 11:10 AM on October 12, 2015


Response by poster: Thank you! A Macbook Pro, about two years old. OS X Version 10.8.5
posted by pipti at 11:15 AM on October 12, 2015


What software is it prompting you to upgrade?
posted by jeffamaphone at 11:17 AM on October 12, 2015


Response by poster: The automatic prompts...when I click on it, it's the App store.
posted by pipti at 11:24 AM on October 12, 2015


Are you trying to do the install from a non-Admin user account?
posted by Thorzdad at 11:32 AM on October 12, 2015


Response by poster: I don't think so--I'm the *only* user of this computer...
posted by pipti at 11:37 AM on October 12, 2015


Can you tell us the exact message it's giving you? Also, maybe a longshot, but I just updated to El Capitan and ran into a snag at that point when my laptop wasn't plugged in. I plugged it in and then the upgrade continued after a minute or two.
posted by yasaman at 11:53 AM on October 12, 2015 [1 favorite]


I would add that you should make sure the laptop is plugged in, and also I would unplug any USB external drives, etc, just to make sure you're not confusing it.
posted by Major Matt Mason Dixon at 11:55 AM on October 12, 2015


Something similar happened to me.. I was able to download El Capitan, but when I tried to install via Software Update I got the same error. I was able to install after restarting my Mac in safe mode, then going to my Applications folder and opening the downloaded El Capitan Installer. Restarting in safe mode might not even be necessary...
posted by homesickness at 11:55 AM on October 12, 2015


Response by poster: I'm plugged in with no external devices. The exact message I get is in the "Install OS X" window and the message is "OS X cannot be installed on 'Macintosh HD.' And underneath is a picture (I guess) of Macintosh HD--a round arrow going counterclockwise inside a clock-like icon. Does that provide any useful clues? Will try restarting and opening the downloaded El Capitan installer.
posted by pipti at 11:59 AM on October 12, 2015


Does that provide any useful clues?

It sounds like it's trying to install an update on your TimeMachine drive which is maybe not on or not where the OS is. Is it possible (and I am sorry if this is a totally left field suggestion) that you deleted the wrong hard drive at some point in the process?
posted by jessamyn at 12:04 PM on October 12, 2015


If the "round arrow" is the Time Machine icon, then the problem may be that the OS X installer thinks that your hard drive is a Time Machine backup disk.

I would try homesickness' advice to reboot and install in safe mode. If you are running Time Machine, I would also try turning that off and purging the local backups.
posted by AndrewInDC at 12:05 PM on October 12, 2015


Response by poster: Yes! Time Machine is a clue! It did once (but not more than once) say something about Time Machine and how it couldn't be backed up. (Sorry not more clear, this was a while ago and it hasn't repeated the message since.) Will try homesickness' suggestion now.

I doubt I deleted the wrong hard drive because I don't think I've ever deleted anything :)
posted by pipti at 12:08 PM on October 12, 2015


Response by poster: Yes, it is telling me "This disk is used for Time Machine backups" and while I've certainly been lazy about backing up, I'm not sure why it's withholding the OS update as punishment...
posted by pipti at 12:15 PM on October 12, 2015


At some point your main hard drive was used as a Time Machine backup drive, or something on your computer is leading the installer to believe this is the case. Try these directions: https://support.apple.com/en-us/HT203322
posted by mikeh at 12:18 PM on October 12, 2015 [1 favorite]


Response by poster: Thanks everyone. I solved my immediate problem with a workaround and will address the Time Machine / OS update soon.
posted by pipti at 5:38 AM on October 13, 2015 [1 favorite]


Yes, it is telling me "This disk is used for Time Machine backups" and while I've certainly been lazy about backing up, I'm not sure why it's withholding the OS update as punishment...

The idea is that your Time Machine backup is actually on an entirely separate external device, an actual physical hard drive that's plugged in to your main computer. See here. That way if something goes drastically wrong with your main hard drive in your laptop, your documents and info are stored on another drive that you could access. If you're using the hard drive in your computer as a backup and the drive goes kaput, your backups won't do any good - you can't retrieve your info from a hard drive that's dead.

So if you've set up Time Machine to back up on your laptop's main hard drive, basically your system "thinks" that your hard drive is *just* for backups, and you're not actually using it as your main hard drive. But your OS is supposed to be stored on your main hard drive. So the install process is "confused".
posted by soundguy99 at 7:32 AM on October 13, 2015


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