Mac OS X Yosemite 10.10 is another product in Apple’s line of Mac OS X. Apple, in its line of amazing Mac OX titles, launched the Mac OS Yosemite 10.10 which took the world by storm. It’s new improved features allow even greater synchronization between iPhones and Macs when using the Internet. Bootable USB Stick - macOS X El Capitan 10.11 - Full OS Install, Reinstall, Recovery and Upgrade. I prefer using a USB key to reinstall Mac OS X (basically like the clean install you described), but Internet Recovery is so easy if you have broadband that it’s a great option. Very glad most Macs have this these days, I believe it’s any Mac that shipped after mid-2011 that includes the Internet based Install OS X ability, I used it on a. But to install or reinstall a recent version of OS X, you must either download a non-bootable installer from the Mac App Store or (via OS X’s invisible, bootable recovery partition) download 6GB.
- Erase And Reinstall Mac Os X
- How To Reinstall Mac Os X El Capitan
- Reinstall Mac Os X Yosemite
- Reinstall Mac Os X El Capitan
For an OS X El Capitan installation, the file gets saved as a disk image named 'InstallMacOSX.dmg'. To install, open the disk image and run the installer named 'InstallMacOSX.pkg'.
Reinstall macOS. Select Reinstall macOS from the utilities window in macOS Recovery, then click Continue and follow the onscreen instructions. Follow these guidelines during installation: If the installer asks to unlock your disk, enter the password you use to log in to your Mac. If the installer doesn't see your disk, or it says that it can't install on your computer or volume, you might need to erase your disk first. If you purchased the computer from someone else who installed El Capitan using their Apple ID you cannot reinstall it, you must sign into the Mac App Store using your ID and download the latest Mac OS that is available for your machine. OS X El Capitan Installer. Official OS X El Capitan Installer from the Mac App Store. Un-archive the zip archive and you will get the app Installer. A bootable ISO or bootable USB can be made from this installer. Instructions on how to do that are on the Internet/Youtube.
When OS X shipped on a DVD a good number of years ago, you always had the convenience of a bootable installer—an OS X installer that could be used to boot your Mac if its own drive was having problems. But to install or reinstall a recent version of OS X, you must either download a non-bootable installer from the Mac App Store or (via OS X’s invisible, bootable recovery partition) download 6GB of installer data from Apple’s servers during the installation process. In other words, you no longer have the same safety net or convenience.
Because of this, I recommend creating your own bootable El Capitan (OS X 10.11) installer drive on an external hard drive or USB thumb drive. If you need to install El Capitan on multiple Macs, using a bootable installer drive is faster and more convenient than downloading or copying the entire installer to each computer. If you want to erase the drive on a Mac before installing El Capitan, or start over at any time, you can use a dedicated installer drive to boot that Mac, erase its drive, and then install the OS (and subsequently restore whatever data you need from your backups). And if your Mac is experiencing problems, a bootable installer drive makes a handy emergency disk.
(OS X Recovery lets you repair your drive and reinstall OS X, but to perform the latter task, you must wait—each time you use it—for the entire 6GB of installer data to download. At best, that’s a hassle; at worst, it’s hours of waiting before you can get started.)
As with previous versions of OS X, it’s not difficult to create a bootable installer drive, but it’s not obvious, either. I show you how, below.
Keep the installer safe
Like all recent versions of OS X, El Capitan is distributed through the Mac App Store: You download an installer app (called Install OS X El Capitan.app) to your Applications folder. In this respect, the OS X installer is just like any other app you buy from the Mac App Store. However, unlike any other app, if you run the OS X installer from that default location, the app deletes itself after it’s done installing OS X.
If you plan to use the OS X installer on other Macs, or—in this case—to create a bootable installer drive, be sure to copy the installer to another drive, or at least move it out of the Applications folder, before you use it to install the OS on your Mac. If you don’t, you’ll have to redownload the installer from the Mac App Store before you can use the instructions below.
What you need
To create a bootable El Capitan installer drive, you need the El Capitan installer from the Mac App Store and a Mac-formatted drive that’s big enough to hold the installer and all its data. This can be a hard drive, a solid-state drive (SSD), a thumb drive, or a USB stick—an 8GB thumb drive is perfect. Your drive must be formatted as a Mac OS Extended (Journaled) volume with a GUID Partition Table. (Follow this tutorial to properly format the drive if you’re using OS X Yosemite or older. If you’re using OS X El Capitan, use these instructions.)
Your OS X user account must also have administrator privileges.
Apple’s gift: createinstallmedia
In my articles on creating a bootable installer drive for older versions of OS X, I provided three, or even four, different ways to perform the procedure, depending on which version of OS X you were running, your comfort level with Terminal, and other factors. How to make bootable mac os usb from windows. That approach made sense in the past, but a number of the reasons for it no longer apply, so this year I’m limiting the instructions to a single method: using OS X’s own createinstallmedia tool.
Starting with Mavericks, the OS X installer hosts a hidden Unix program called createinstallmedia specifically for creating a bootable installer drive. Using it requires the use of Terminal, but createinstallmedia works well, it’s official, and performing the procedure requires little more than copying and pasting.
The only real drawback to createinstallmedia is that it doesn’t work under OS X 10.6 Snow Leopard—it requires OS X 10.7 Lion or later. Though it’s true that some Macs still running Snow Leopard can upgrade to El Capitan, I think it’s safe to assume that most people installing OS X 10.11 will have access to a Mac running 10.7 or later.
Reinstall Os X From Usb Flash Drive
(If you absolutely refuse to go near Terminal, an El Capitan-compatible version of DiskMaker X is now available, although I haven’t yet had the chance to test it.)
Making the installer drive
- Connect to your Mac a properly formatted 8GB (or larger) drive, and rename the drive
Untitled. (The Terminal commands I provide here assume that the drive is named Untitled. If the drive isn’t named Untitled, the procedure won’t work.) - Make sure the El Capitan installer (or at least a copy of it), called Install OS X El Capitan.app, is in its default location in your main Applications folder (/Applications).
- Select the text of the following Terminal command and copy it. Note that the window that displays the command scrolls to the right.
- Launch Terminal (in /Applications/Utilities).
- Warning: This step will erase the destination drive or partition, so make sure that it doesn’t contain any valuable data. Paste the copied command into Terminal and press Return.
- Type your admin-level account password when prompted, and then press Return.
- You may see the message “To continue we need to erase the disk at /Volumes/Untitled. If you wish to continue type (Y) then press return:” If so, type the letter Y and then press Return. If you don’t see this message, you’re already set.
The Terminal window displays createinstallmedia’s progress as a textual representation of a progress bar: Erasing Disk: 0%… 10 percent…20 percent… and so on. You also see a list of the program’s tasks as they occur: Copying installer files to disk…Copy complete.Making disk bootable…Copying boot files…Copy complete. The procedure can take as little as a couple minutes, or as long as 20 to 30 minutes, depending on how fast your Mac can copy data to the destination drive. Once you see Copy Complete. Done., as shown in the screenshot above, the process has finished.
Reinstall Os X From Usb 3.0
Createinstallmedia will have renamed your drive from Untitled to Install OS X El Capitan. You can rename the drive (in the Finder) if you like—renaming it won’t prevent it from working properly.
Booting from the installer drive
Reinstall Os X Lion From Usb
You can boot any El Capitan-compatible Mac from your new installer drive. First, connect the drive to your Mac. Then, restart your Mac (or, if it’s currently shut down, start it up) while holding down the Option key. When OS X’s Startup Manager appears, select the installer drive and then click the arrow below it to proceed with startup. (Alternatively, if your Mac is already booted into OS X, you may be able to choose the installer drive in the Startup Disk pane of System Preferences, and then click restart. However, sometimes OS X installer drives don’t appear in the Startup Disk window.)
Reinstall Mac Os X From Usb
Once booted from your installer drive, you can perform any of the tasks available from the OS X installer’s special recovery and restore features. In fact, you’ll see the same OS X Utilities screen you get when you boot into OS X Recovery—but unlike with recovery mode, your bootable installer includes the entire installer.
Recently, I reinstalled macOS on my device. Throughout the process, manyattempts failed miserably. But I now have some experience and assorted hints onwhat to try.
DISCLAIMER: All information in this post is provided as-is, and some of it mayvoid your warranty. Neither Chris Warrick nor Apple will be responsible for anydamage to your devices caused as a result of using information in this post.
Contents
The best, safest, least error-prone way to do an install is with a USB stick.Unfortunately, making a USB stick with the macOS installer on it is a nuisance.The expected way to produce macOS install media is to download the installerfrom App Store/Software Update, and run the createinstallmedia command-lineprogram included with that installer app. All is well, as long as macOS works.If it doesn’t, and Recovery can’t install it for you, that can be difficult tosolve.
Apple does not make macOS images publicly available. That’s probably to makeHackintoshing this little bit harder, but this also affects legitimate users.The only thing you can download from Apple is El Capitan. Apple offersInstallMacOSX.dmg on theirwebsite. If you take a look at the instructions, you will see that this isnot a bootable OS X image. This image has a .pkg package. This package isexpected to install /Applications/Install OS X El Capitan.app. Well, we’rein recovery, we can’t install stuff. So, let’s do this the manual way.
Turns out the .pkg format is just an archives all the way down, with allarchives being different formats (at least three).
The first archive is the .pkg file itself. Those files are in XAR format, which was invented by theOpenDarwin community. You can either extract it with pkgutil --expandfoo.pkg foo_files (the last argument is the destination directory, can beanything, will be created by pkgutil) if you have access to that command (it’savailable in Recovery OS), or you can try the xar utility as xar -xffoo.pkg. The structure produced by both tools is a bit different, but we canwork with both.
The second archive-in-archive is the Payload. It’s a gzipped cpio archivethat contains the files installed by this package. If you have BSD tar(default on macOS, easily installable on Linux), you can just do tar -xvf Payload.Otherwise, you can use gunzip -c Payload | cpio -i (or gzcat). Thatwill extract all the files the package has.
Another nested archive is the Scripts archive, although note thatpkgutil will extract it automatically. If it’s not extracted, it’s actually.cpio.gz again, with the same way to extract it.
(PS. If you have 7z around (on Windows/Linux as well), you can just pointit at all the compressed files mentioned in this paragraph.)
Let’s expand the El Capitan package.
We’ve got the installer app, which is what we need to create an install image.Great, let’s try it!
Erase And Reinstall Mac Os X
Oh, we’ve got a problem. Turns out there’s one more thing we need to take careof, and it’s the scripts. MacOS packages have scripts, typically shell scripts,that are run at various stages in the install process. We can look at thePackageInfo file, or just look in the Scripts folder, to see thatthere’s an link_package script we need to run. This script creates aContents/SharedSupport directory inside the installer app, andcopies/hardlinks the InstallESD.dmg file (which is the install formerly-DVDimage) to that directory. Let’s try doing this on our own:
How To Reinstall Mac Os X El Capitan
And it works! createinstallmedia will now produce valid install media.
If you are in Recovery, you can find an Install app on the filesystem. If youtry to run it, you will get the same error as in the previous paragraph:
This also happens with some older macOS versions, where you get a small.app from the App Store, and that app does the actual download.
Whatever the issue was, we need to download the install files with theinstaller. Open the installer and let it run until the download finishes. Ifthe app asks you to reboot, quit it at this point. If it never asks, you canstill find a way to get files out (after a failed install, they should not beremoved).
The install files can be found in /macOS Install Data on the destinationvolume. For older versions, you will just have InstallESD.dmg, newerversions add more and more files, some of which are hardware-specific (andCatalina has InstallESDDmg.pkg, because Apple loves nesting archives for noreason!). However many files you find, you can just:
Copy
Install macOS Catalina.appto a read-write volume.Copy the contents of
/Volumes/TARGET/macOS Install DatatoInstallmacOS Catalina.app/Content/SharedSupport. Make sure you account for hiddenfiles, if any (copy the entire directory). If you did this correctly,InstallESDDmg.pkg(orInstallESD.dmgon older verisons) is in theSharedSupportdirectory (not in a subdirectory).Run
createinstallmedia. It should now consider the installer valid. Theavailable options differ slightly depending on the OS version.
If you get this error, it might be because Apple’s signing keys expired, orbecause of other date/time weirdness. Regardless, you can force an install ifyou are sure the installer is not damaged with this command (source):
While messing with all the installer stuff, I found out a fewinteresting/worrying things about the download process.
The first one is that the macOS installer uses plain HTTP without encryption todownload files. That opens you to all the standard issues — an attacker canreplace files you download, and the protocol doesn’t do anything to detecterrors (the installer will verify files, but where do the checksums comefrom?).
The second one is how the download happens. You might have noticed it to be abit slower than usual traffic. The download happens in 10 MB chunks, using theRange HTTP header. The installer asks for 10 MB, gets it, saves, asks foranother chunk. Repeat that over 800 times, and the overhead of the entire HTTPdance becomes noticeable. (I haven’t checked, but I hope the installer at leastuses Keep-Alive. I wouldn’t be particularly surprised if it didn’t, though.)
But this raises another question. The servers clearly support partial downloads.And yet, if your network disconnects during the download, your downloadprogress for that file is reset, and in Catalina, you can go from 8 GB back to500 MB if you’re particularly unlucky. The question is, why? Thisinfrastructure should make it trivial to continue the download, perhapsdiscarding the most recent chunk if you’re concerned about that download of itbeing unsuccessful.
The first time you boot a Mac after a clean install, it starts the SetupAssistant. This app asks for basic OS settings (locale, date/time, useraccounts), and also lets you restore user data from backups.
Sometimes, you might want to access the Terminal or Console from that screen.You can do that with Ctrl + Opt + Cmd + T and Ctrl + Opt + Cmd + C respectively (source).
How could that come in handy? For example, if you want to check if the backupdrive still worked and if the process isn’t stuck (I wrote a test file and alsochecked top).
A few months later, in December, I upgraded to Big Sur and then installed Windows 10alongside it in Boot Camp. I then did some more hacks, which led totwo unbootable OSes.
As part of the upgrade, I had prepared install media and used it to install (soit wouldn’t fail, as it did last time), and made a .dmg of it with DiskUtility. (Also, Apple won’t tell you this, but you need to give Disk UtilityFull Disk Access for disk imaging to work. Otherwise, you get a crypticerror.) I erased the USB drive after installing, but hey, I could get it back.I booted into Internet Recovery and restored my image. Big Sur failed to bootand showed a 🚫 sign. I triedrestoring my Catalina image from the previous reinstall, and that didn’t workdue to a size mismatch. I used a different USB drive than these months ago (Ididn’t have that one with me at the moment), and apparently the one I used hada different size (both are marketed as 16 GB). The images could be mountedfine, and createinstallmedia should have worked, likely producing abootable drive.
Time Machine is Apple’s magical backup solution. Time Machine saves snapshotsof your entire disk. It’s supposed to help restore files that were deleted orchanged in an unwanted way, or help you restore a full macOS install.
Time Machine is great at file recovery, but none of my 3 system restoreattempts were successful. Attempt #1 was a full Time Machine System Restore,from Recovery, back in June. It failed partway through, it couldn’t readeverything from the disk. There might have been underlying hardware issues withthat failure, so I had another attempt.
Attempt #2 was a Migration Assistant restore, as part of the initial setup.This one succeeded, and things worked… except for one fairly important app.This app requires online activation with the vendor, and it wouldn’t reactivateafter the install. Whatever the third-party vendor is doing didn’t like thereinstall. I tried to nuke all the things in ~/Library related to theirsoftware, and ran their nuke-everything uninstaller, but that didn’t work.I reinstalled from scratch and copied over my files, settings and apps from theTime Machine drive.
Attempt #3 involved the System Restore again, this time for the Decemberreinstall. The hardware issues were all fixed in the meantime, so I went for aTime Machine System Restore.
Reinstall Mac Os X Yosemite
Issue #1: Internet Recovery booted into Catalina. There was an issue on Apple’sside, Big Sur was unavailable in Internet Recovery in December. TMRecovery will not restore a backup created with a newer version of macOS thanyou’re booted into, so I was forced to restore a slightly older Catalinabackup. (I spent most of my time in Windows during that weekend, so other thanthe need to upgrade macOS to Big Sur again, I didn’t really lose any data dueto this.)
Issue #2: It wasted time computing an inaccurate size estimate. Beforerestoring a backup, macOS first checks if it will fit on your drive. When itdoes that, an indeterminate progress bar is shown. macOS won’t tell you theresult of that computation, but you can read the final value from the fullInstaller Log (Cmd + L). On my Mac, the value was 96.2 GB. I was at the Macwhen it was getting close to that value. 94, 95, 96, 96.1, 96.2, 96.3… hold ona second, 96.3 GB? Hopefully that’s just a bunch of extra things that areinstalled from the system image directly, or something like that, right? Ofcourse, since the progress bar is based on the pre-computed size, it becameindeterminate and I couldn’t tell when it would end. 98, 100, 110, 120, 121.2GB is where it ultimately ended. So, not only did it waste 20+ minutescomputing a size, it was off by 25 GB.
Reinstall Mac Os X El Capitan
Issue #3: The restore didn’t work. The System Restore finished and claimed tohave succeeded, but macOS wouldn’t boot. It showed an Unrecoverable error,SecurityAgent was unable to create requested mechanism. Most people who had asimilar error had it caused by a botched TeamViewer uninstall; I didn’t havethat installed, and it was referring to a different component. So, wipe andfresh reinstall it is.
I copied my stuff from the TM drive, and it was acting weird. Some apps failedto load their settings copied into Library, others started with a “Move to/Applications?” prompt (even though they were in that directory). For somereason, those files had some hidden attribute set on it. I worked around it byputting files in a .zip archive with Keka, and then unzipping them;xattr might also help. (The attribute was likely com.apple.quarantine.)
After I got the Mac to work, I reinstalled Windows and set up rEFInd, and itnow works fine. (I only use rEFInd because I want virtualization in Windows,and that doesn’t work unless you’re warm-rebooting from macOS. I don’t needanything more advanced than the Option key boot menu, but Apple made me use athird-party bootloader.)
We now go back to the original post from June.
Dear Progress Bar Designers: can you please make your progress barsfunctional? The macOS progress bar might look sleek at just 7 px (non-Retina)/6pt = 12 px (Retina) high, but at the same time, you’re looking at individualpixels if you need to know if it works or if it’s stuck. I have had to point mymouse cursor at the end of the filled-in part just to know if it’s working ornot. Or sometimes, put a piece of paper in front of my screen, because there isno mouse cursor when macOS installs on the black screen. How to makethat progress bar easier to use and more informative? Just add numbers on top ofit. For long-running processes, I wouldn’t mind progress bars that said“12.34%”. That specific Setup/Migration Assistant window should be changed (itonly has a remaining time estimate and transfer speed, it should also showmoved data/total size), but wouldn’t more things benefit from a clearindication of the progress? Yes, perhaps it looks less sleek, perhaps itrequires more space for the bar.
Just compare: which is easier to parse? Which is more informative?
I’d honestly be happy enough with option 2, at least it can be read easily andyou can remember the number instead of a vague position.
After all this, I managed to get macOS Catalina installed. After variousfailures in built-in El Capitan recovery and Catalina Internet Recovery, I firstinstalled El Capitan with this hack, then jumped to Mojave because I thoughtthe new Software Update would help (it didn’t, same installer, samefailed-to-extract-package issue), then made a Catalina USB stick, and itfinally clean-installed, but I was worried about the backup disk’s operation,and I used a proxy on my local network to try and speed up Catalina downloadswithout much improvement… but hey, at least it works. Apple should really makeit easier to install their OS and to make boot media even when stuff doesn’twork, even from Windows. The Hackintosh folks can just find someone with aworking Mac and ask them to download from App Store and make install media, orfind less legitimate sources, they probably don’t care as much. But if my ownsystem crashes, I’d probably want to get working install media immediately,myself, and from Apple. Without all this mess.