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Mac OS X updating FAQ

If you need technical support for issues after reading this FAQ, please visit my Tech Support page, where I offer fee based support. Before upgrading, please Backup your data!!

Note: this FAQ does not cover 10.1.5 or earlier. For that you will need to go to Old Mac OS X Speed. This Frequently Answered Question (FAQ) page is divided into these sections

Why should I read this FAQ?

As of the writing of this FAQ (Frequently answered question page), I've updated every Mac OS X version on an Intel Mac through 10.4.11 to 10.11 using the method of this FAQ. I have a PowerPC Mac right now standing at 10.4.8, which I could upgrade to 10.4.11, except I have some old games which won't run on 10.4.11. Just because you've seen an issue which appears on a bulletin board, or is reported to you by a friend in a Mac OS X update, it does not mean the update is itself bad. A mathematical improbability exists to test all combinations of software and hardware compatible with Macs. The fact the update works at all is a testament to how well tested the software is. As a result an update may appear on the surface to be bad, but in reality a contributing factor is causing your problem. If I had a complete failure with no contributing factors, I'll list it in this update page. So before you go and blame an update on your problem, try and look for contributing factors, and always backup your data prior to updating. The steps below should help you avoid the most common mistakes in updating and avoid the most common contributing factors.

10.12 Sierra

Sierra was released September 20, 2016
You may find software compatibility sites already stating what is compatible with it. Do not trust those reports, until those reports are published after the official release of Sierra. Apple may elect to change features at the last second, as it has done on countless operating system improvements before. Note, download times may be longer than usual on first release. Backup (link explains how) your data before you install anything.

Apple had kept the same minimum hardware requirements for Mac OS X 10.8 through 10.11. 10.12 requirements have changed the minimum requirements.

Here are the requirements with the Machine ID (x,x) as stated in the System Profiler for Mac OS 10.12 Sierra:

MacBook (Late 2009 or newer) 6,1

MacBook Pro (Mid 2010 or newer) 6,1

MacBook Air (Late 2010 or newer) 3,1

Mac mini (Mid 2010 or newer) 4,1

iMac (Late 2009 or newer) 10,1

Mac Pro (Mid 2010 or newer) 5,1

This information is available on Apple's Sierra Requirements page

10.11 Notes:

Same minimum system requirements exist under Mac OS X 10.8 and later. iPhoto has special notes under 10.10 Notes

There are known Microsoft Office issues, addressed by Microsoft on their knowledgebase.
Software tested before that date may not work with the operating system. Some anomalous POP E-mail. issues have been reported on Apple Support Communities. IMAP e-mail is by default server based, and if you trust your internet provider to back it up, may be a better solution. Moving from POP to IMAP is something you have to do with care, since by default POP is based on storing everything on your Mac. Make sure to backup your Users -> yourname -> Library -> Mail and Mail Downloads folders if you are using Apple Mail before upgrading.

There are also issues with signatures not working at all in Mac OS X Mail.

AccountEdge has also noticed there is a bug when mailing PDFs directly from Mac OS X Mail. They recommend using the Print window's built-in PDF -> Mail PDF function when you go to print a PDF.

You should really at least backup everything to two separate destinations that are not touched by the computer before upgrading or until after the upgrade is complete. Be sure to look at Roaring Apps for compatible applications that are compatible, and ignore entries prior to September 30, 2015 stating they are El Capitan compatible. RAW updates for 10.11. exist here:

Download 1844.

Printer and scanner driver issues with Yosemite are covered with more details on my Mac OS X printers page.

Lastly El Capitan has scrubbed Repair Permissions from Disk Utility. This means you'll have to rely on an Apple update that includes it to repair your permissions. Look for combo updates you can apply repeatedly. Of course 10.11.1 does not have a combo update.
10.11.2 through 10.11.6 have also been made available. There is a command line repair permissions option if you really need it.

10.10 Notes:

Yosemite was released 10/16/2014. Same system requirements as 10.9. Software tested before that date may or may not work at third party download sites. Additional Yosemite updates from 10.10 to 10.10.5 may be found on my page Mac OS X Updates Jaguar and above, and further security updates may be found on Apple Support downloads Be sure to look at Roaring Apps for compatible applications that are compatible, and ignore entries prior to October 16, 2014 stating they are Yosemite compatible.

iPhoto is dropped by Apple in favor of a new Pictures Application. For some, keeping iPhoto is important past Mac OS X 10.10.2. If you are one who likes it, this Apple Support Communities user tip explains how you can keep it.

10.9 Notes:

On February 25, 2014, a critical security flaw was corrected in all versions of 10.9 with the 10.9.2 update (earlier versions of Mac OS X are unaffected): 10.9.2 Combo. A similar flaw was corrected on iPhones, iPad, iPod Touch with the iOS updates below (iOS 5.x and earlier are unaffected).

Users of iOS 6 or later should upgrade to 6.1.6

Users of iOS 7 or later should upgrade to 7.0.6

On October 22nd, 2013, Apple released 10.9 Mavericks for a free download for anyone with Mac OS X 10.6.8 or later and the same hardware requirements as 10.9. Compatibility though may vary from 10.8. Like 10.8 and 10.7 before it, there is no Rosetta (PowerPC Mac, pre-2006) application compatibility except through a hack. Epson and Canon drivers were released immediately after 10.9's release. Backing up your data prior to installation, should be done as always. Links for the drivers, and other bugs are currently noted on this user tip Be sure to look at Roaring Apps for compatible applications that are compatible, and ignore entries prior to October 22, 2013 stating they are Mavericks compatible.

10.8 Notes:

10.8.5 is now available. Before you upgrade, be sure to read the tips below for upgrading. This user tip I wrote on Apple's board covers the scope of my knowledge about Mountain Lion. Be sure to look at Roaring Apps for compatible applications that are compatible, and ignore entries that predate Mountain Lion's release July 25, 2012.

10.7 Special Notes:

From my user tip on Apple Support Communities, that is currently being considered, I'm mirroring the info on my website. Note, there is now a Supplemental update to 10.7.5 which should be applied after backing up your data and making sure your software and hardware is 10.7.5 compatible. These are the most common Lion Q and As that are able to be answered as of this time. Additional answers will come as soon as we've had a chance to upgrade.
Q: What are the system requirements of the Lion upgrade?
A: Core2Duo, Core i3, i5, i7, and Xeon Intel CPUs with 2 GB of RAM in a Macintosh computer with 2 GB of RAM, and 4 GB (7 GB after installed) for downloading from the Mac App Store (Available in 10.6.6 and later). Unofficially, past upgrades have arbitrarily also required an additional 15% of the hard drive to be free for data.

Q: What applications are compatible with Lion?

A: provides a nice third party editable listing for people to include the compatible applications. Many of these compatibility entries came from before Lion's release. Please verify they are correct now that it has been released, and help edit it for more accurate data. Be sure to include any update version of Lion post release that you have found is or is not compatible with it, for the help of others who may be upgrading to Lion the first time. Additionally, as it was released, there is no Rosetta. This means any application that is stated to be PowerPC in the System Profiler, will not work with Lion, and needs a comparable application or upgrade to be compatible. The System Profiler is in Apple menu -> About This Mac -> More Info. Intel and Universal applications are on the whole supported, though may still need some tweaking before every feature is compatible.

Q: Are there any pitfalls to watch out for?

A: With all upgrades, backing up your data at least twice has been a given. Hardware can fail independently of downloads and upgrades, though may happen simultaneously. Software may be found to be incompatible that has not been tested with the new upgrade, or combination of other software that might be installed with the upgrade. It is also strongly recommended once your backup is complete, to shut down your computer, remove all but Apple wired keyboard and mouse (notebooks remove all input devices). Then once done, reboot, and go directly to the upgrade distribution system available. Third party system tools, modification, and "maintenance" applications should be verified as compatible, or removed until known to be compatible. Check with developers how to remove if it is essential to use Lion before those applications become compatible. Most "maintenance" tools that deal with system cache, prebinding, are not really maintenance tools. Ask on forum when are the appropriate times to use them before assuming they should be used for upgrades or otherwise.

10.7.4 introduces some new pitfalls, which hopefully will be resolved soon, as both home sharing and internet sharing don't work as well as expected.

Q: How can I get from 10.4 or 10.5 to 10.6.6?

A: Purchase a 10.6 retail installer from an Apple retail or third party reseller. It has a picture of a Snow Leopard on the DVD, and does not say Upgrade, Dropin, or OEM. Install it, and then install the 10.6.6 combo update from:
Q: Is it true that I can only get it from the Mac App Store?

A: No. Apple offered a $69 USD version on a thumb drive. Some may not like the security a thumb drive offers a DVD. You can install on it on a DVD or Thumb drive presently, which I'll explain later how to do, as long as you honor to the license agreement of the Mac App Store. The Thumb Drive still requires 10.6.6 minimum be installed for an upgrade and install, however, an erase and install can be done without purchasing 10.6 or 10.5 for Intel Macs that have older operating systems. Of course this means losing all the data on the machine unless it is backed up. If you feel Apple should still offer a DVD, you can post feedback here:

Q: If you do not create a thumb drive or DVD of Mac App Store version, or wait for the Thumb drive, what limitations can I expect?

A: First off the 7 GB space limitation on the hard disc after it is installed. Secondly, the size of the download file requires significant time, unless you have a high speed broadband connection. Times expected are below -

4 GB at:

5Mbps is 2 hours.

at 1 Mbps is 10 hours.
at 384 kbps is 27 hours.
at 56k kbps is 184 hours (nearly 8 days).

If you include the 10.6.6 combo update of 1.06 GB

add 29 minutes for 5 Mbps

145 minutes (2 and 25 minutes) for 1 Mbps

6 and a half hours for 384kbps

A 24 hour day and 15 hours (for a total of a minimum of 39 hours) for 56kbps

Remember the retail 10.6 currently does not include the App Store, and those upgrading from 10.5.8 or earlier will need to both buy the retail 10.6, and download the combo 10.6.6 update, not to mention ensure they have the correct processor and 2 GB of RAM. Finally once it is available, you'll have find out how long approximately it takes to install after the download is complete.

These times do not include installation time, which on a MacBook Pro 3,1 15" installing on a Firewire 800 Newertech Voyager with WD10ACS-322J80 drive, 10.6.7, took 1 hour and a half to complete the installation from double clicking the install command to the registration screen. These times may vary by connection speeds from a non-dedicated connection, or background application usage of the internet. Any applications running when the installation process begins might interfere with the installation itself, and they should be quit first.

Q: How do I create a Flash Drive or DVD installer from the Mac App Store version within license agreement terms?
A: First off, note, Apple has announced a $69 version on a Flash drive will become available for those without high speed internet in August 2011. If waiting that long for Lion compatibility is not desirable, the installer just before it starts has in its package contents an InstallESD.dmg file a DVD burnable image to install on additional computers in the home without downloading over again. So if you desire to reinstall without an extra internet download, extract that file, by selecting the installer in the dock, and control-clicking it, and revealing it in the Finder. Next Control-mouse click it, and select show package contents. Inside that folder is a Shared Support folder. That's where you find the called InstallESD.DMG. Disk Utility can then be used to restore that DMG to either Flash drive or burn a DVD as long as you keep within the number of copies and location of copies the license agreement gives you license to use.

Q: If I purchased a Mac recently, can I get it cheaper?
A: Yes, visit for details.

Q: When did Lion become available?

A: It became available July 20, 2011 at the Mac App Store. Later in August a USB Flash drive version is expected to come to stores.

Q: Which Macs can run Lion?

A: Look at Apple menu -> About This Mac -> More Info, and see if you meet the Machine ID and RAM requires under the hardware. 2 GB is required for all These Machine IDs will run Lion:
Mac Mini 2,1 and later

MacBook 2,1 and later.

iMac 5,1 and later.

All MacBook Air.

MacBook Pro 2,1 and later

All MacPros.
The Macs with the Machine IDs below will not run Lion (x can be any number):
Mac Mini 1,x or PowerMac x,x

MacBook 1,x

MacBook Pro 1,x

iMac 4,x, 3,x, 2,x, 1,x

10.6 Special Notes

10.6.8 Security Update 2012-001 & Rosetta bug
Guest Account bug - data loss
10.6.4 nVidia OpenGL
10.6.8 Hands Off bug
10.6.7 font bug

10.6.8 Security Update 2012-001 & Rosetta bug

Security Update 2012-001 version 1.1 is now available through the original download link and Software update. The bug affected Rosetta (programs that used PowerPC CPU from pre-2006 Macs) drivers and applications. If this doesn't solve the problem, please report to Apple Apple Feedback and AppleCare

10.6.8 Hands Off bug

A user reports that Hands off 1.2.4 can cause a kernel panic, and upgrading to version 1.3.1 fixes the issue in Mac OS X 10.6.8. The user report on Apple Support Communities, and the software in question can be downloaded from Metakine's website.

10.6.7 font bug

Apple released a patch to address issues with fonts for 10.6.7 on April 26, 2011. it is in the knowledgebase article HT4605

Guest Account

WARNING: If you use Guest accounts in Snow Leopard, a bug has been that wipes the guest account contents entirely. 10.6.2 is supposed to fix this bug. Currently being researched by some people on Apple Discussions as to the cause. It may related to an earlier 10.4 bug that I indicated below, about using the Migration Assistant between PowerPC and Intel Macs. Instead if you have done so, be sure to backup at least twice and if necessary, rename the Guest account something else and give it admin access until the issue has been resolved. You can also migrate from PowerPC to Intel Macs using the user tip on:

10.6.4 nVidia and OpenGL bug

This bug may affect ATI and Intel GPU chipsets as well, though nVidia is the first to attempt to write updated driver updates to address it. 10.6.4 appears to not ask the GPU for enough power to access OpenGL based software, including many games that need it for performance. Note, you may have to backtrack, so be sure to backup a copy of your 10.6.4 system without this patch, so if Apple releases an update to address it, you can be sure to apply the update as Apple had originally intended it to be updated. Adding nVidia's patch may be too different from what Apple was expecting to patch. If you have a GTX 285 card, here are their drivers GeForce-MacOSX-19.5.8f03-driver.html.

Snow Leopard update requirements

August 28, 2009, Apple introduces Snow Leopard, Mac OS X 10.6. The first operating system totally divorced from PowerPC Macs. This means if you have one of these machines: You won't be able to upgrade to Snow Leopard, until you buy a newer Mac, introduced 2006 or later. Those Macs are the Mac Pro, the Intel iMacs, The MacBook, MacBook Air, MacBook Pro, and 4 and 5 USB port Mac Mini with a minimum of 1 GB of RAM (You can find this in Apple menu -> About This Mac. 512 MB, 540 MB, 640 MB, or 768 MB of RAM won't cut it).

Furthermore, there are C!Net Download, Wikipedia, Macintouch websites now for Snow Leopard compatibility. If you find an error, please edit the Wiki and e-mail Macintouch. Apple now has a document about what it does when it finds incompatible software for 10.6 during the installation process.

Snow Leopard gets rid of third party Contextual Menu Items. Thus if any application you have relies on them, you'll have to find an alternative application.

At the very minimum before installing Snow Leopard, backup your data at least twice, and dismount and disconnect all third party peripherals.

Apple has now added to its knowledgebase compatible scanners and printers for 10.6.

Some peripherals that run through System Preferences will only run if the Get Info box for System Preferences is set to 32 bit mode. When System Preferences is not open, Go to Hard drive -> Applications, and click ONCE on System Preferences, and select Get Info from the File menu to find the checkbox to toggle 32 bit and 64 bit mode.

Special Notes for 10.5 and above

Special Notes for 10.4.8 through 10.4.10

In reverse chronological order, these have been found to be issues with the particular updates:

At least since 10.4.4, it has been possible for Macs to lose sound in some applications while not others. How to configure the Audio Midi Application to fix this problem has been documented with a solution on Apple's Knowledgebase article 300832. Zapping the PRAM has also solved this problem, as long as the clock battery (also known as backup battery. Some Macs where it says n/a have a capacitor which could age as well) is less than 4 years old.

10.4.10 reportedly has a bad audio issue whereby sounds turn into pop on the speakers which now has been fixed with the Audio Update 2007001 Intel, or 10.4.10 Intel Combo Update 1.1. I've not experienced this thus far, and I just installed 10.4.10. Also there were issues reported with airport, firewire, and USB, all of which I could not reproduce upon initial tests. It goes to prove the methods below still work. If you have issues with any of these and 10.4.10, I suggest posting a new topic thread on Apple Discussions Installation and Setup for Tiger board.

iTunes 7.3,1, Quicktime 7.2, and Rosetta:
It has also been found that some people who have installed the Developer Preview version of Java 6, or Developer Preview version of the Developer Tools may incur broken Rosetta when installing iTunes 7.3.1 or Quicktime 7.2. One problem some may find is that if they are running a Rosetta compatible application while installing these updates, they may break Rosetta.

If updating from a PowerPC to Intel Mac, or migrating vice versa, do not use the Migration/Setup Assistent. Instead use Target Disk Mode, or some form of networking, or sharing media to move only those files that are safe to migrate from one operating system to the next. If you have questions what can be moved, feel free to e-mail me.

10.4.9 has been found to have a longer eject key response than previous Mac OS X versions, and trouble sharing with AFP in Mac OS 9 if Mac OS 9 initiates the connection to a shared Mac OS X folder. The latter can be fixed by making Mac OS X initiate the connection following my instructions.

Adaptec 2906 drivers may no longer work with 10.4.9. As a substitute Atto's drivers were found to be able to work on some configuration.
A system administrator named Sinjin Lindbeck contacted HP technical support and discovered that repairing permissions would fix this problem they described to me:
"If running OS 10.4.9 and your HP printers, scanners, etc start losing print jobs into the ether or fail intermittently, perform a repair disk permissions to eliminate the problem. I spent about 4 hours on my own and finally called HP. They said it was a problem with their drivers and 10.4.9. Just thought I'd share."
Repair permissions is in Applications -> Utilities -> Disk Utility.

10.4.8 has been found to have an issue with WiFi (Airport) on Intel Macs, and solutions are currently still being sought for these issues. Not all Intel Macs are affected, and most likely if you follow the suggestions below when you do upgrade, you won't have trouble with the update. Given that people have noted certain issues, I've posted their solutions which have been found on my website. Also Apple is aware of issues with RAID volumes according to article 304511.
Apple also has an Knowledgebase article about troubleshooting software updates, at: which may also help you here.

If dmgs don't open after an update, move these files to the desktop and restart:

Special thanks to robsterc and Mac OS X hints for that solution Additional solutions are being found on this this thread.

Installing full version versus partial version updates

Installing a full version update (i.e. to 10.2, 10.3, 10.4) requires all the following precautions, in addition to understanding the different kinds of installation available. Full version updates are not free and are available only on CD or DVD. The partial version updates which the rest of this FAQ discusses are free for download if you have the correct full version on your system. I.e. These partial versions will update these full version systems for free:
Full version 10.0 have 10.0.1, 10.0.2, 10.0.3, and 10.0.4 as updates.
Full version 10.1 have 10.1.1, 10.1.2, 10.1.3, 10.1.4, and 10.1.5 as updates.
Most of the following partial version updates have Apple links still available, which I link to directly off my Jaguar to El Capitan update table:
Full version 10.2.x (where x means any number), can be updated to 10.2.1, 10.2.2, 10.2.3, 10.2.4, 10.2.5, 10.2.6, (10.2.7 only was released for certain G5 Macs), 10.2.8
Full version 10.3.x can be updated to 10.3.1, 10.3.2, 10.3.3, 10.3.4, 10.3.5, 10.3.6, 10.3.7, 10.3.8, 10.3.9
Full version 10.4.x can be updated to 10.4.1, 10.4.2, 10.4.3, 10.4.4, 10.4.5, 10.4.6, 10.4.7, 10.4.8, 10.4.9, 10.4.10, and 10.4.11
Full version 10.5.x has 10.5.1, 10.5.2, 10.5.3, 10.5.4, 10.5.5, 10.5.6, 10.5.7, and 10.5.8 as updates.
Full version 10.6 has 10.6.1, 10.6.2, 10.6.3, 10.6.4, 10.6.5, 10.6.6, 10.6.7, 10.6.8, and 10.9*, 10.10*, and 10.11 as updates.
Full version 10.7 has 10.7.1, 10.7.2, 10.7.3, 10.7.4, 10.7.5, 10.7.5 supplemental, and 10.9*, 10.10*, and 10.11 as an updates.
Full version 10.8 has 10.8.1, 10.8.2, 10.8.2 supplemental update, 10.8.3, 10.8.4, 10.8.5, and 10.9*, 10.10*, and 10.11 as updates.
Full version 10.9 has 10.9.2, 10.9.3, 10.9.4 10.9.5 and 10.11 as updates.
Full version 10.10 has 10.10.1, 10.10.2, 10.10.3, 10.10.4, 10.10.5 and 10.11 as updates.
Full version 10.11 has 10.11.1, 10.11.2, 10.11.3, 10.11.4, 10.11.5, and 10.11.6.
Later in this FAQ there are more finite details on how these updates may be obtained and for which platform they are available.
* 10.9 through 10.11 have been available freely through the Apple App Store, except 10.9 & 10.10 are only available now to people who bought Macs with those operating systems prebundled on them. You may be able to request one to become available for specific software compatibility, or check Apple Usergroups to find if someone has held the original installer in its full image. If you meet the same specs as 10.8 10.9, 10.10, and 10.11 should work. Although each includes new software, which may require more space in the end.

Also note, for Mac OS X 10.4 and 10.5, Apple released them on DVD-ROM. If your Mac does not have a DVD-ROM compatible drive, you will need to get a Firewire DVD drive that is Mac OS X bootable (such as those by Otherworld Computing, or others listed on XLR8yourmac), or the previously sold by Apple Media Exchange Program replacement CDs (only available for 10.4). The disks will look like black disk with white X logo. They may be available at one of the Used and Refurbished Mac shops.

System Specific restrictions

System Specific Disk Restriction note:
It is important to note, that installation of operating systems from a different Mac model will not always work right. Use only the disks which come with the Mac in question, or newer retail disks up to the hardware limits of the Mac in question (retail disks for Mac OS X look like, white disc with orange 9 logo for Mac OS 9, white disc with aqua X logo 10.1 (Puma), white disc with Jaguar fur colored X logo for 10.2 (Jaguar), black disc with serifed letter X for 10.3 (Panther), black disc with san serif letter X for 10.4 (Tiger), a sans serif X overprinting a pink and white colored galaxy for 10.5 (Leopard), and image of snow Leopard under text for 10.6 Snow Leopard. There has been much debate about this, however, a user tip, and these knowledgebase articles all point towards that fact:

If you are having trouble identifying which Mac OS system specific disc you need for your Mac, use my guide on identifying Macs.

Steps for avoiding update failures

The following fourteen suggestions apply to all updates, with a 15th suggestion of how to downgrade if you find yourself here after you updated unsuccessfully:

1. Turn off any system that automatically updates. This includes the following:
2. Backup (link goes to software available for backing data) your data at least twice before any update, and make sure you always have at least two copies of all your data on another media that won't be affected by the update. The reasoning of this is two fold, if the update causes you to not be able to access the media you have your backup on, you'll have another set of media that you can access it from once you erase and install an older operating system. And if you keep an extra set of backups of your data, keep them in a safe place in case something happens to the place your computer is at. This includes having a backup copy of the system update to get you to the prior system without too much hassle after an Archive and Install, as described in step 14 of this FAQ.

3. Make sure the programs you need to run either require that version of the operating system to run, or can run on that operating system. If all the programs you need and drivers you need can run on your current system, don't upgrade! If it isn't broken, don't fix it.

Along the lines of this train of thought, Apple has released security updates that require specific operating systems to run. Most recently, update 2012-001 for 10.6.8 version 1.0 disabled certain Rosetta (Rosetta indicates pre-2006 PowerPC CPU based programs) applications and drivers. Version 1.1 repairs it. Repairing Permissions may fix this issue. Permissions repair is no longer an option in Mac OS X 10.11. However, there is an excellent discussion on Malware on Apple Support Communities for things you can do to stave off both Malware and Adware.

Unfortunately these updates may not always jibe with your existing software compatibility. If security is important to you, be sure to take normal security precautions until you are able to update to a more secure system. Such precautions include the following:

4. Updates necessitate in most instances a repair of permissions before and after. Which instances those are is still unclear, even though Apple makes no judgement call as to when to repair permissions. But given that numerous people have found updates failed when permissions weren't repaired, and I've seen it happen to myself, I recommend it. I do not recommend using any cache repair, prebinding software, or other swiss army knife utility to do this. Only use Disk Utility or the Repair Privileges utility depending on your Mac OS X version. In Mac OS X 10.2 through 10.4.9, repair permissions has been available through:
Hard drive -> Applications -> Utilities -> Disk Utility -> select hard disk in Disk Utility -> click on First aid

Mac OS X 10.1.5 was the first version of Mac OS X where permissions could be repaired using a special Repair Privileges Utility.

5. They require you have at least 3.5 GB (for 10.2 or 10.3), 4.5 GB (for 10.4), 9 GB (for 10.5 Leopard) of disk space free (more if you burn CDs or DVDs with the Finder. For every CD or DVD burnt with the Finder you'll need an additional equivalent space to the media you are burning) before you install the update. An arbitrary 15% empty has been found to be best for Mac OS X in addition to this amount. In the end that means for Leopard if you have a 100 GB hard drive 24 GB needs to be free.

This amount of space is significantly decreased by 10.4's improved CD and DVD burning, though not completely eliminated. Articles 61339 and 302276 explain pre-Tiger and Tiger's burning methods respectively. In Mac OS X 10.3, your hard disk free space is located in the Finder's View menu -> Show Status bar which appears at the bottom of any Finder window. See my How to free up my disk space FAQ to help you clear your disk of non-essential files.

6. They require you don't have any third party peripherals attached. If one of those peripherals is a data storage medium like a hard drive, camera media, or removable media, drag its icon to the trash before detaching the peripheral and make sure its icon is not appearing in the Finder sidebar or when you Go to Folder /Volumes/ if it isn't there.

7. Make sure automatic Energy Saver settings for hard disk are turned off. If the hard disk spins down while the update is being performed, the update may not complete. Apple menu -> System Preferences -> Energy Saver has options to allow the hard drive to stay awake.

8. Check that any peripherals or third party addon cards you are using don't require a firmware update before you update the operating system. If by accident you did leave a hard drive that required a firmware update, you may only be able to see that hard drive after the update using Prosoft Engineering's Data Rescue, or moving that hard drive into another hard drive case. To avoid that problem, be sure to dismount (drag its icon to the trash on the dock) and disconnect drives prior to performing an update. This page has links to various kinds of software and hardware support pages for Mac OS X: Also, before upgrading to Mac OS X 10.2 or higher, you must upgrade your system's firmware if it needs it. Otherwise you'll end up with a blank screen.
As part of this, you'll need to know how Apple identifies those Macs. There is a new section on the Mac OS X native page which helps in identifying your Mac.

Once your firmware is up to date, make sure your clock battery isn't too old. Once it is over 4 years old, it may need replacing. All desktop Macs that will run Mac OS X use a standard 1/2 AA 3.6 V battery, you can buy at Radio Shack (catalog item 23-026). The iMac G4, G5, Intel, Mac Mini, eMac, and Notebooks though use a specialized battery that only a service center can replace known as a backup battery on Apple's article 86181. Some notebooks have no backup battery, and use a capacitor instead. For those that use a capacitor and end up unbootable, sometimes a zap of the PRAM helps. Zapping the PRAM can be done also on machines with known good batteries. Never zap your PRAM unless you know the battery is newer than 4 years. Even an almost totally drained battery can cause problems before the clock resets itself on the computer.

9. Check any third party system utility programs you use and haxie type software don't need to be updated before you update.

10. Make sure all Apple Applications are stored in the same folder they were in when you first installed the operating system, otherwise they may not get updated.

11. Make sure the hardware doesn't have any problems according to Apple's Hardware Test CD. The Hardware Test comes in three varieties. Those for early Macs that will install Mac OS X which are stand alone silver colored disks that came with your Mac. These you can boot from Apple menu -> System Preferences -> Startup Disk, the 'C' key, or the Startup Manager (Intel version, PowerPC version). If you lost the original disks that came with your Mac, Call AppleCare for replacement disks. If you bought the machine and they didn't come with the original disks, contact the seller and ask them for the disks, or for them to Call AppleCare if they lost them. The seller can not hold on to the original disks as they are only licensed for use with machine they came with.

12. When installing the update, and this has been true at least through 10.4.8, the "Combined" (combo) update will sometimes work better than the "Delta" and/or Software Update version of the update, or even repair issues that happen with that update. The updates are listed on this Jaguar 10.2 through El Capitan 10.11 updates tables page. The "combined" (combo) updates are the ones that can update more than just one operating system version. The delta updates can only update the preceding system version. If you choose to use software update, and it does not appear to be working, follow these tips by Apple in Article 106695.

13. If the update does not apply itself correctly it may give you an error that it failed to install. Be sure if this happens to reapply the "combined" (combo) update as mentioned in step 12.

14. When updating, make sure you have a healthy system before you update. Some utilities to measure a healthy system can themselves cause problems to prevent an update from being successful. Ask a technician if you are currently having issues with cache, fonts, or the directory, before attempting to use such utilities. If you attempt to use them without first having a backup (mentioned earlier), you could be in worse shape, than first backing up. This also means if you have anything that won't run on your system that is supposed to be able to run, fix that before updating! An update will only add new features, and refine others. Fix any issues which may cause kernel panics and directory problems before updating. In addition, make sure you don't have any bad preference, permissions, font, or cache issues using the utilities on the Mac OS X speed FAQ. If you have any doubt about the health of your system, ask the Mac community if something is abnormal first before updating.

15. If you need to downgrade to see if an issue existed before your update, you can Archive and Install and apply the previous combined (combo) update. Note, this will only work with Mac OS X 10.2 through 10.3.9. Later and Prior versions of Mac OS X require you erase and install Mac OS X to get to the previous operating system version. Note, when installing an older operating system, be sure to delete any Apple applications which existed in the older operating system installation first before proceeding, or move them to a folder where Apple's installer won't see them (i.e. someplace other than Applications or Applications -> Utilities folder) as some of those newer versions of applications won't work in the older operating system. Either method requires you already have a working backup system (link goes to software available for backing data) in place, as the problems you may be having may be directly related to your hard drive. In which case, only replacing the hard drive and recovering from your backup will work. In addition, Archive and Install is the recommended way to upgrade to any newer retail version of the operating system starting with 10.2. Do not use the installer disks from another Mac, or the Upgrade disks to do this Archive and Install, unless your Mac qualified for the 10.2.7, 10.2.8 to 10.3 up to date program which went on from October 8th through 25th 2003. For those Macs, you need to Archive and Install the 10.2 disks that came with them, and then use the Upgrade disks from the program to Archive and Install again! Another note, family pack CDs do exist, and they offer a chance to install Mac OS X on more than one computer as long as the Mac can install that version of Mac OS X. The following article helps define which version of Mac OS X came with which Mac, and what minimum OS X version can be installed: Apple Knowledgebase article 25517 and 1159. Downgrade suggestions I posted on Apple Discussions as a more difficult, as this User Tip illustrates. The good news is, now Mac OS X Mail 10.4 can be converted back to a format that 10.3 Mail understands, thanks to two utilities: emlx converter and Emailchemy.

Mathematical Improbability of testing all software

Rather than bore you with the details, I've put this section at the bottom of the FAQ for those who are interested in seeing why I say a mathematical improbability exists. The Apple Guide, which was available prior to the Mac App Store listed over 23000 items that are Mac compatible. There is no way in the age of the known universe (given modern science's guess of about 10^13 to 10^27 years), that even a catalog of 63 possible hardware and software titles can be tested with every possible combination. Math says you need to use factorials for such calculations and Google calculates 63 factorial seconds as 10^79 years.

Additional Sources

My primary Mac website lists many other Mac help pages as well as discussions boards where you can ask questions about the compatiblity of updates with your system. Always check the Mac community to see if certain updates have pitfalls you may not be aware of before updating.