Date: 6/24/2018
OS: macOS Sierra Version 10.12.6 (updated last week and then didn't use my laptop until yesterday)
Dropbox version: v52.4.58
Dropbox account: Personal, 71% of 15.4GB used
Enough space on local drive.
Have tried "full" uninstall described here (https://help.dropbox.com/desktop-web/advanced-reinstall) several times. But it is still not working.