Just rename “.dropbox” and “.dropbox.dist” in your home directory. I also removed the dropbox package and installed it again, but I don't think it's necessary. Then, type "dropbox start"; the program will complain and ask you to type “dropbox start -i”. Do it, it will download the private part of the program and that's all.
The source of the problem were were the old “.dropbox” and “.dropbox.dist”.
Rename ONLY .dropbox-dist (not .dropbox) UNLESS you want to forget your old settings.
THEN run "dropbox start -i" ... that's it, let it update and you are done. No idea why it can't update itself. Real pain in the *** dropbox crew. Been this way for years now ... makes me think they don't care much about the Linux community. Hope they fix this problem.