XCode 4.2 installation from App Store failing

Question

When trying to install Xcode 4.2 update from App Store, it is failing with the following error messsage.
installd[561]: PackageKit: Install Failed: Error Domain=PKInstallErrorDomain Code=123 "The update was cancelled because the application integrity could not be verified." UserInfo=0x106a514c0 {NSURL=file://localhost/var/folders/b9/prfhtrfj7bz1921l9my0k5v00000gn/C/com.app le.appstore/448457090/mzm.lwqivlnf.pkg#InstallXcodeLion.pkg, PKInstallPackageIdentifier=com.apple.pkg.InstallXcodeLion, NSLocalizedDescription=The update was cancelled because the application integrity could not be verified.} {
              NSLocalizedDescription = "The update was cancelled because the application integrity could not be verified.";
              NSURL = "file://localhost/var/folders/b9/prfhtrfj7bz1921l9my0k5v00000gn/C/com.apple.app store/448457090/mzm.lwqivlnf.pkg#InstallXcodeLion.pkg";
              PKInstallPackageIdentifier = "com.apple.pkg.InstallXcodeLion";
Is this a package error of Xcode 4.2 installer or is there a remedy?

Answer 1

I have experienced the same issue two times, and the third download (done after a reboot) have works properly. I have no clue about what goes wrong, but during the last download, I have caught the downloaded file in case of a repeated failure to be able to test it manually without another download. Since it works, it was useless, but if you want to do so, here is how you may proceed:
While the file is still being downloaded, run the following command in terminal to determine its name:
~$ find /private/var/folders -newerct '1 minute ago' -print
From the output, you should find a .pkg file, that is of the size of the currently downloaded part. To capture it, simple run the following command:
~$ ln /private/var/folders/some/temporarypath/com.apple.appstore/temporaryfolder/temp oraryfile.apk InstallXcodeLion.pkg
using the correct file name of the file found.
This will create a hard link to the file in the current folder, and the file will never be deleted (until the current folder is deleted or you deleted obviously).
The file I captured that way has exactly 1 806 581 275 bytes and the following SHA1 checksum:
~$ shasum -b InstallXcodeLion.pkg
1d3048d87097f872fab15c77264e4a2ed43cfd74 */Users/me/InstallXcodeLion.pkg
Hope this helps those with a limited bandwidth to diagnose the possible source of this issue, not downloading again uselessly.