Unable to update safari due to "Spotlight is using the SafariQuickLookPreview extension" Error message: 


  Spotlight is using the SafariQuickLookPreview extension, which must be
  closed before the software can be installed.




I have already closed safari. 

What do I need to do to update safari?
This seems to work for me.

Go to Activity and search for 'safari':



Pick the entry 'SafariQuickLookPreview (Spotlight)' entry and kill it.

Then use the 'Try Again' button in the 'Software Update' pane in System Preferences.