Apple - The operation can’t be completed because the original item for “Foo” can’t be found

Apparently this problem can occur for many different reasons. In my case it was solved by re-launching the finder. A description and solution for this was at http://www.cnet.com/news/fix-shared-computer-not-found-in-finder/ .

To fix this problem, you simply need to relaunch the Finder, and it will re-populate the list of shared devices. To do this, you can do one of the following:

• Hold the Option key and right-click the Finder icon in the Dock, then select Relaunch.
• Press Option-Command-Escape or choose Force Quit from the Apple menu, then select the Finder and click Relaunch.
• Log out and log back in to your user account.

In my case (iMac trying to access files on a Win7 machine) the solution was to add permissions for "Guest" to the Win7 directory. This was previously not necessary. The directory was shareable to everybody and it worked. But apparently now the iMac is trying to connect as "Guest" and adding permissions specifically for "Guest" (Properties…Sharing…Share…Add…Guest) solved it.

Ok so I am going to answer my own question. In my case the solution turned out to be really 'simple'.

I looked at another Mac and I noticed that the /Volumes directory had different permissions. On the problematic Mac it was set to drwxr-xr-x and on a recently installed Mac it was drwxrwxr-x.

So I fixed my problem with:

sudo chmod 775 /Volumes

(You can also do that in the Finder of course, via Get Info)

Problem solved. I can now mount any file share again.