Q: Mountain Lion Install Fails on late 2010 MacBook Pro

Repair the Hard Drive and Permissions

Boot from your Snow Leopard Installer disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Utilities menu. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list.  In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive.  If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the installer.

If DU reports errors it cannot fix, then you will need Disk Warrior and/or Tech Tool Pro to repair the drive. If you don't have either of them or if neither of them can fix the drive, then you will need to reformat the drive and reinstall OS X.

Repair the Hard Drive and Permissions - Lion

Boot to the Recovery HD:

Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.

Repair

When the recovery menu appears select Disk Utility. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list.  In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive.  If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported then click on the Repair Permissions button. When the process is completed, then quit DU and return to the main menu. Select Restart from the Apple menu.

Yes, you should be able to do that via the Setup Assistant or the Migration Assistant.

I had the same problem with the disk needing repair. I resetted the PRAM and it has now installed perfectly. i didn't need to do a new disk repair.

I also am having the same problems. In DU verify disk confirms "This disk needs to be repaired. Click Repair Disk." However Repair Disk button is gray - not available. Verify permissions produced a long list of entries saying permissions differ and repair disk permissions is also not available. How do you reset the PRAM? Should I try this before doing a reformat? Thanks

Yes, there was nothing wrong with my HDD so don't reformat.

To reset PRAM restart and hold command option P and R keys simultaneously before the chimes. The screen should flick to black and then it will restart again.  After that I ran the installer and all worked fine. Now on Mountain Lion.

Thank You! I appreciate your response as I will probably try ML one more time. In the meantime since I had a time machine backup I restored from that and did verify disk in DU which was ok. Verify disk permissions produced a long list of permissions differ but the repair option was available so I did that. Everything in permissions was repaired except this:

Warning: SUID file “System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/MacOS/ARDAg ent” has been modified and will not be repaired.

I wonder if this caused the initial problem but I am glad to have the computer functioning again in Lion. I have reservations that ML is worth all the trouble after reading so many posts about problems during and after installing it.

In any case thanks to you and all of the other technical folks that help us who are technically challenged!

Just wanted to report that I had the same problem, and solved it only by wiping the computer and starting over.

The problem: I tried to upgrade to Mountain Lion on a late-2011 Macbook Pro. The installer hung and then returned an error, "OS X Mountain Lion couldn't be installed, because the disk Macintosh HD is damaged and can't be repaired."

What didn't work: I tried the following, to no avail.

• Deleted and re-downloaded the installer to try again. Got the same message.
• Ran disk utility, both booting as normal and booting from the recovery hard drive (accessible by restarting and holding Cmd-R). It said it was repairing Display.pref each time, but never really fixed it -- each time I ran "Repair Permissions," it said it would say that the permissions for this are incorrect and would repair the same thing. Re-running the installer returned the same error.
• Tried to reinstall Lion by booting from the recovery disk. Now it said, "OS X  Lion couldn't be installed, because the disk Macintosh HD is damaged and can't be repaired." Since I had no problems before trying to upgrade to Mountain Lion, my conclusion is that Mountain Lion installer actually damaged my system somehow, preventing a normal reinstall of the existing Lion operating system.

What did work: I was finally able to fix everything by completely wiping the hard drive and starting over. The following procedure worked for me.

1. Do a Time Machine backup to make sure everything's up to date.
2. Restart and hold Cmd-R to boot from the recovery drive. Then run Disk Utility.
3. Click your hard drive (Macintosh HD in my case), choose the "Erase" tab and erase. Erase your hard drive.
4. Close Disk Utility and click the option to reinstall Lion.
5. Once installed, Lion will run its setup wizard. At the appropriate moment, choose "Restore from Time Machine" to put everything back the way it was (this can take quite a while depending on how much stuff you have). After your stuff was restored, it's worth poking around a bit to make sure everything's in order, e.g. open Mail, iPhoto, etc.
6. Open the App Store and re-download and install Mountain Lion. (It worked fine for me at this point, although it took an unusually long time, and at some point the installer indicated that there was "negative" minutes left before installation was complete.)

Conclusion: the Mountain Lion updater seems to contain a pretty serious bug. Web-searching to deal with the problem reveals that the bug has really effected a lot of people. This is exactly the kind of Microsoft-style disaster that I expect to avoid with the Apple brand. As Merlin Mann once put it, I pay Apple a little more for impeccable design, insanely great build quality, and an assurance that I won't find my iD*ck slammed in a door on day zero. There is no excuse for a glitch this big still existing 10 months after release.