“Macintosh HD” can’t be opened because the original item can’t be found.

Right I had this issue as well.

The way I fixed was as following:

1. Open a Finder window.
2. Open Finder Preferences.
3. In the 'Devices' section of the 'Sidebar' tab, click the option for your device name. In my case it's "Thomas's MacBook Pro".
4. In the Finder window, go to the Devices section in the sidebar. You should see your device name.
5. Click into this in the Finder - you should see your HD. Drag and drop this into the favourites or wherever you like and this should work as a new link. You can then remove the original link from the sidebar.

Hope this helps!

Try pressing Cmd+Spc > type Disc Utility press enter and select your Macintosh HD there verify the HD is mounted and run first aid.

How exactly are you trying to open "Macintosh HD" in Finder?

What happens if you do the following? In Finder, use the Go menu to navigate to "Home". A window should open with its title being the name of your home directory. Command click on the title of that resulting Finder window. Can you select Macintosh HD there?

I went to "computer" on the Go menu and "Macintosh HD" was listed as a file on the resulting screen. It worked normally when I clicked it. The dead link was still on the left-hand sidebar of the Finder window. I drug and dropped the working icon/file onto the left-hand sidebar and I noticed it had a slightly different icon than the dead link now listed above it. I deleted the dead link and the new one seems to be working fine.

Thanks for your response. I had to take it in to the techs at Apple Store to get this and other problems addressed, so, now, a few weeks later cannot remember exactly what they did to correct it, but all's fine now.

Alternatively: From the Finder Go menu, select "Computer". In the resulting Finder window what do you see?

Went to Disk Utility. "Unmount" is there but not highlighted. Ran First Aid anyway, with result indicating all is ok with the disk.

This.