iMovie 10.0.1 Upgrade/Install Fails With "an error has occurred" Message
To investigate the problem, please run Console to check the recent logs for more details (look for com.apple.installd).

In example, I had something like:

com.apple.launchd[1]: (com.apple.installd[69518]) Job appears to have crashed: Abort trap: 6
ReportCrash[69520]: Saved crash report for installd[69518] version 332 to /Library/Logs/DiagnosticReports/installd_2014*.crash


If you see the crash in your logs, then check the backtrace under System Diagnostic Reports, so there is something like:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSKeyedUnarchiver initForReadingWithData:]: incomprehensible archive


The reason for that could be that some of the downloaded files are corrupted.

So to solve that, you have to remove these files and try again.



Simple solution


Quit your App Store
Run Finder and go to (CMD+Shift+G): /private/var/folders.
Trash all the folders from that folder (e.g. vp, zz).
Run App Store and re-try.


In case something bad happens, restore these removed files from your Trash.



Advanced solution

From Terminal check if you've temporary files here:

ls -la /private/var/folders/*/*/*/com.apple.appstore


And then try to remove them (you may backup them first just in case):

rm -frv /private/var/folders/*/*/*/com.apple.appstore


Warning: Make sure you won't do any typos (like adding space between the folders), as you could remove the wrong files!

And re-try to run installer again.



Related:


https://discussions.apple.com/thread/4483444
https://discussions.apple.com/thread/4234582