Unable to copy OSX Installer from external drive to Mac As usual I wanted to prepare bootable USB with OSX. Some time ago I've made a copy of my Mavericks, Yosemite and El Capitan to external drive.

I wanted simply to drag &amp; drop El Capitan to prepare USB drive.

After dragging El Capitan app file to desktop I get



The point is, that my Desktop does not contain this file. What's wrong? The same happens to all 3 files. I cannot copy them. Are those files corrupted? In a meanwhile I'm downloading new file form App store...

This disk was plugged into Windows multiple times. Is it possible that Windows damaged app files? I've noticed that Windows treats app files as folders so maybe it changed the content?
This is a known bug in the Finder app of OSX. Options you can try : 


Instead of drag-dropping you can try right click -> Copy Item and
then paste it on the desktop
Try copying the files through terminal command.
Try making a folder on the desktop, and then copy the files in the newly created folder.


Reference : Apple Discussions.