As of today Dropbox is permanently stuck on "upgrading Dropbox". I'm running Dropbox in Linux. I've found references to such error messages a good while back by Googling, but no simple fix.
I was in the same situation as the others here on the current opensuse level. I tried to adapt ngtr's solution without really understanding it and got into a situation where dropbox was trying to reinstall - and then hanging on 98% - on every new session.
Running "dropbox start" from the command line showed that something was looking for "libatomic.so.1" so I installed the newest libatomic package (not the gcc7 one, that would have been next) and now everything appears to work again.
I thought libatomic-ops-dev was gcc7 based, the libatomic1 I installed is based on gcc8. There was no research on my part when I installed it, it was a case of "see if this works". It did.
I don't know how anyone else approached this but I entered "dropbox start" in a console-window and the error message made it clear what was missing.
I have a second machine which also uses Dropbox and which was also exhibiting the same symptoms. So I installed libatomic1 there, logged out and logged in again. Dropbox then announced that it was "Up to date".
Strange is: I had reinstalled Dropbox on my first machine and now have 85.4.155 there. This second machine claims to have 84.4.170 but is "Up to date".
This is still ocurring, i.e. Linux update is failing and stalling the Dropbox service.
$ ./dropbox.py status
Upgrading Dropbox...
If you have downloaded the above python "dropbox.py" script from the Dropbox Linux page, you can do the following to at least get the Dropbox service running again:
