A quick note on this. I did a 10.10.5 upgrade last night on two machines. One worked fine. The other did not. It was my primary work machine. Yahoo. My issue was that after it was all done there was the standard error reporter saying Pages was corrupted and delete it and restore it from the App Store. Of course, after I did that and hit OK there was another one. In fact there was about 20. And other apps did not work either. I could click on them and they would blink and not start. VMware Fusion was the only one that would start but it errored out and said not compatible with this OS.
So I thought I would do as the computer said – download the apps and they would be fine. NOT so I found out. Same behavior.
Apple said to boot to Recovery (Option + R) and reinstall the OS. I did and it took about 30 minutes.
All now working. Except for all those apps I deleted. Those are coming back one at a time as I need them.
Apple confirmed that the ReInstall through the Recovery option should not harm or delete data or settings or apps.
BTW, if this did not work, I had a Time Machine backup, Back Blaze backup, and a Super Duper image backup. But I wanted to help Apple deal with in case others have the problem.
Hope that this helps!
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