Mendeley Desktop on my Mac at work had silently stopped working - clicking the button in Launchpad did nothing. Navigating to the directory on the shell, cd “/Applications/Mendeley\ Desktop.app/Contents/MacOS/” it appeared a prior update had broken halfway through, leaving a null file for ‘Mendeley Desktop’. Whoops. However there was a ‘Mendeley Desktop.bak’. Running this from the shell, Mendeley Desktop appeared, and then offered to update itself, this time completing successfully.