Software update for iTunes gives an error. Please help.

Question

It gives an error while performing a software update to iTunes 12.0.1
Error as seen below:
The update “iTunes” can’t be installed.
An unexpected error occurred.
My current iTunes version from About iTunes is 11.4(18) 64 bit
I saw few of them posting their install.log from console which I am putting for reference. Please help to update the version.
Marker - Dec 17, 2014 11:43:08 AM
Dec 17 11:45:36 Mihirs-MacBook-Pro Software Update[754]: JS: 10.7.5
Dec 17 11:45:37 Mihirs-MacBook-Pro diskmanagementd[769]: DM ->T-[DMToolBootPreference recoveryPartitionInfoForVolume:what:dict:]: inHostDiskUDS=0x107a39c20=disk0s2=Macintosh HD inWhatStr=RecoveryInfoBaseSystemVersion
Dec 17 11:45:38 Mihirs-MacBook-Pro diskmanagementd[769]: DM ..T-[DMToolBootPreference recoveryPartitionInfoForVolume:what:dict:]: did get booterRecoveryUDS=0x107a39ae0=disk0s3=Recovery HD
Dec 17 11:45:39 Mihirs-MacBook-Pro diskmanagementd[769]: DM ..T-[DMToolBootPreference recoveryPartitionInfoForVolume:what:dict:]: did mount nobrowse; MP=/Volumes/Recovery HD OMS=0x7f9903006430
Dec 17 11:45:39 Mihirs-MacBook-Pro diskmanagementd[769]: DM ..T-[DMToolBootPreference recoveryPartitionInfoForVolume:what:dict:]: getting dict from file=/Volumes/Recovery HD/com.apple.recovery.boot/SystemVersion.plist
Dec 17 11:45:39 Mihirs-MacBook-Pro diskmanagementd[769]: DM ..T-[DMToolBootPreference recoveryPartitionInfoForVolume:what:dict:]: got dict (or NULL=will return err): oooInfoDict=0x7f9901419cb0
Dec 17 11:45:40 Mihirs-MacBook-Pro diskmanagementd[769]: DM ..T-[DMToolBootPreference recoveryPartitionInfoForVolume:what:dict:]: did if-needed-best-effort unmount
Dec 17 11:45:40 Mihirs-MacBook-Pro diskmanagementd[769]: DM <-T-[DMToolBootPreference recoveryPartitionInfoForVolume:what:dict:]: retErr=0 outInfoDict={
     ProductBuildVersion = 11D2001;
     ProductCopyright = "1983-2012 Apple Inc.";
     ProductName = "Mac OS X";
     ProductUserVisibleVersion = "10.7.3";
     ProductVersion = "10.7.3";
Dec 17 11:45:48 Mihirs-MacBook-Pro Software Update[754]: JS: 10.7.5
Dec 17 11:45:51: --- last message repeated 1 time ---
Dec 17 11:45:51 Mihirs-MacBook-Pro Software Update[754]: JS: Firmware is up to date.
Dec 17 11:45:51: --- last message repeated 1 time ---
Dec 17 11:45:51 Mihirs-MacBook-Pro Software Update[754]: JS: model = MacBookPro8,1
Dec 17 11:45:52 Mihirs-MacBook-Pro Software Update[754]: JS: 10.7.5
Dec 17 11:46:01: --- last message repeated 4 times ---
Dec 17 11:46:01 Mihirs-MacBook-Pro Software Update[764]: Acquired Lock: 501, 754, 0
Dec 17 11:46:01 Mihirs-MacBook-Pro Software Update[764]: Releasing Lock: 501, 754, 0
Dec 17 11:46:27 Mihirs-MacBook-Pro Software Update[754]: Calculated need 1870.195 MB; 317806.137 MB free; 317806.137 MB available with MTM reclaim
Dec 17 11:46:27 Mihirs-MacBook-Pro Software Update[764]: Acquired Lock: 501, 754, 0
Dec 17 11:47:58 Mihirs-MacBook-Pro installd[760]: PackageKit: ----- Begin install -----
Dec 17 11:47:58 Mihirs-MacBook-Pro installd[760]: PackageKit: request=PKInstallRequest <5 packages, destination=/>
Dec 17 11:47:58 Mihirs-MacBook-Pro installd[760]: PackageKit: packages=(
     "PKLeopardPackage <file://localhost/Library/Updates/zzzz031-08056/iTunesX.pkg>",
     "PKLeopardPackage <file://localhost/Library/Updates/zzzz031-08056/iTunesAccess.pkg>",
     "PKLeopardPackage <file://localhost/Library/Updates/zzzz031-08056/CoreFP.pkg>",
     "PKLeopardPackage <file://localhost/Library/Updates/zzzz031-08056/CoreADI.pkg>",
     "PKLeopardPackage <file://localhost/Library/Updates/zzzz031-08056/MobileDevice.pkg>"
Dec 17 11:48:00 Mihirs-MacBook-Pro installd[760]: PackageKit: Will do receipt-based obsoleting for package identifier com.apple.pkg.iTunesX (prefix path=/)
Dec 17 11:48:01 Mihirs-MacBook-Pro installd[760]: PackageKit: Will do receipt-based obsoleting for package identifier com.apple.pkg.iTunesAccess (prefix path=/)
Dec 17 11:48:01 Mihirs-MacBook-Pro installd[760]: PackageKit: Will do receipt-based obsoleting for package identifier com.apple.pkg.CoreFP (prefix path=/)
Dec 17 11:48:01 Mihirs-MacBook-Pro installd[760]: PackageKit: Will do receipt-based obsoleting for package identifier com.apple.pkg.CoreADI (prefix path=/)
Dec 17 11:48:01 Mihirs-MacBook-Pro installd[760]: PackageKit: Will do receipt-based obsoleting for package identifier com.apple.pkg.MobileDevice (prefix path=/)
Dec 17 11:48:05 Mihirs-MacBook-Pro installd[760]: PackageKit: Extracting file://localhost/Library/Updates/zzzz031-08056/iTunesX.pkg (destination=/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/Cleanup At Startup/PKInstallSandbox-tmp/Root, uid=0)
Dec 17 11:48:25 Mihirs-MacBook-Pro installd[760]: PackageKit: Extracting file://localhost/Library/Updates/zzzz031-08056/iTunesAccess.pkg (destination=/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/Cleanup At Startup/PKInstallSandbox-tmp/Root, uid=0)
Dec 17 11:48:25 Mihirs-MacBook-Pro installd[760]: PackageKit: Extracting file://localhost/Library/Updates/zzzz031-08056/CoreFP.pkg (destination=/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/Cleanup At Startup/PKInstallSandbox-tmp/Root, uid=0)
Dec 17 11:48:28 Mihirs-MacBook-Pro installd[760]: PackageKit: Extracting file://localhost/Library/Updates/zzzz031-08056/CoreADI.pkg (destination=/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/Cleanup At Startup/PKInstallSandbox-tmp/Root, uid=0)
Dec 17 11:48:29 Mihirs-MacBook-Pro installd[760]: PackageKit: Extracting file://localhost/Library/Updates/zzzz031-08056/MobileDevice.pkg (destination=/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/Cleanup At Startup/PKInstallSandbox-tmp/Root, uid=0)
Dec 17 11:48:30 Mihirs-MacBook-Pro installd[760]: PackageKit: update_dyld_shared_cache -overlay /var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/Cleanup At Startup/PKInstallSandbox-tmp/Root
Dec 17 11:49:16 Mihirs-MacBook-Pro installd[760]: PackageKit: xpchelper --rebuild-cache --overlay /var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/Cleanup At Startup/PKInstallSandbox-tmp/Root
Dec 17 11:49:26 Mihirs-MacBook-Pro installd[760]: PackageKit: Executing script "preinstall" in /private/tmp/PKInstallSandbox.3wcfFc/Scripts/com.apple.pkg.iTunesX.ClCbhl
Dec 17 11:49:37 Mihirs-MacBook-Pro installd[760]: PackageKit: Install Failed: Error Domain=PKInstallErrorDomain Code=112 "An error occurred while running scripts from the package “iTunesX.pkg”." UserInfo=0x7f9a026b5130 {NSFilePath=preinstall, NSURL=file://localhost/Library/Updates/zzzz031-08056/iTunesX.pkg, PKInstallPackageIdentifier=com.apple.pkg.iTunesX, NSLocalizedDescription=An error occurred while running scripts from the package “iTunesX.pkg”.} {
     NSFilePath = preinstall;
     NSLocalizedDescription = "An error occurred while running scripts from the package \U201ciTunesX.pkg\U201d.";
     NSURL = "file://localhost/Library/Updates/zzzz031-08056/iTunesX.pkg";
     PKInstallPackageIdentifier = "com.apple.pkg.iTunesX";
Dec 17 11:49:38 Mihirs-MacBook-Pro Software Update[764]: Releasing Lock: 501, 754, 0
Dec 17 11:49:38 Mihirs-MacBook-Pro Software Update[754]: Error: An error occurred while running scripts from the package “iTunesX.pkg”. (PKInstallErrorDomain code 112)
I also tried suggestions provided in other forum: Troubleshooting iTunes installation on Mac OS X - Apple Support
I downloaded dmg file from thelink provided and followed the steps. It still gives an error.
Error as below:
The installation failed.
The install encountered an error that caused the installation to fail. Contact the software manufacturer for assistance.
Please help.
Please help to get iTunes install.

Answer 1

Please read this whole message before doing anything.
This procedure is a test, not a solution. Don’t be disappointed when you find that nothing has changed after you complete it.
Step 1
The purpose of this step is to determine whether the problem is localized to your user account.
Enable guest logins* and log in as Guest. Don't use the Safari-only “Guest User” login created by “Find My Mac.”
While logged in as Guest, you won’t have access to any of your documents or settings. Applications will behave as if you were running them for the first time. Don’t be alarmed by this behavior; it’s normal. If you need any passwords or other personal data in order to complete the test, memorize, print, or write them down before you begin.
Test while logged in as Guest. Same problem?
After testing, log out of the guest account and, in your own account, disable it if you wish. Any files you created in the guest account will be deleted automatically when you log out of it.
*Note: If you’ve activated “Find My Mac” or FileVault, then you can’t enable the Guest account. The “Guest User” login created by “Find My Mac” is not the same. Create a new account in which to test, and delete it, including its home folder, after testing.
Step 2
The purpose of this step is to determine whether the problem is caused by third-party system modifications that load automatically at startup or login, by a peripheral device, by a font conflict, or by corruption of the file system or of certain system caches.
Please take this step regardless of the results of Step 1.
Disconnect all wired peripherals except those needed for the test, and remove all aftermarket expansion cards, if applicable. Start up in safe mode and log in to the account with the problem. You must hold down the shift key twice: once when you turn on the computer, and again when you log in.
Note: If FileVault is enabled in OS X 10.9 or earlier, or if a firmware password is set, or if the startup volume is a software RAID, you can’t do this. Ask for further instructions.
Safe mode is much slower to start up and run than normal, with limited graphics performance, and some things won’t work at all, including sound output and Wi-Fi on certain models. The next normal startup may also be somewhat slow.
The login screen appears even if you usually log in automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.
Test while in safe mode. Same problem?
After testing, restart as usual (not in safe mode) and verify that you still have the problem. Post the results of Steps 1 and 2.