Mac-The operation can’t be completed because an unexpected error occurred.

Sometimes mac has a problem while deleting or copying a file .If we trash finder preferences (~/Library/Preferences/com.apple.finder.plist) it fixes the things. Unfortunately Apple hides your library folder now so you need to:

  1. switch to Finder
  2. hold the “option” key on the keyboard
  3. Click on the “Go” menu
  4. Select “Library” (hidden if the option key is not down)
  5. locate the folder “Preferences”
  6. locate the file “com.apple.finder.plist”
  7. move said file to trash
  8. log out
  9. log in
  10. test to see if fixed

Show hidden files Mac OS X 10.7 Lion and 10.8 Mountain Lion

To enable hidden files/folders in finder windows:

Open Finder
Open the Utilities folder
Open a terminal window
Copy and paste the following line in:

defaults write com.apple.Finder AppleShowAllFiles YES

Press return
Now hold ‘alt’ on the keyboard and right click on the Finder icon
Click on Relaunch
You should find you will now be able to see any hidden files or folders. One you are done, perform the steps above however, replace the terminal command in step 4 with:

defaults write com.apple.Finder AppleShowAllFiles NO