I told Dropbox to not backup an external drive; now I've changed my mind

I also have this problem and would really like a solution that doesn’t include reformatting my drive, as I would have to buy a new 2TB drive to do that. Which seems a bit excessive. Thanks in advance for any help!

I'm wondering if Lori from Dropbox (or anyone else) has unsubscribed to this thread since my "solution" of reformatting my drives was marked as accepted. It doesn't seem like there's been a fix for this so maybe a new thread should be opened by someone else who is still having the issue?

Recently I bought a new external SSD and when first plugging it into my 2016 MacBook Pro running Mojave, Dropbox offered to back it up. It's a great function. At the time, because I don't have enough room in my Dropbox account, I chose only a couple of specific folders. I later regretted these settings and wanted to change them, but then realised there seems to be no way to adjust these settings after the backup is established.

So I decided to delete the backup and start over. However, because I had already gone through this process once with Dropbox, it no longer saw this external drive as 'new', so no matter how many times I plugged it in. It just wouldn't see it and give me the pop-up to ask if I wanted to back it up. And, unlike on Windows, there's no option to click on a drive on Mac and tell Dropbox you want to create a backup of that drive.

In the end I contacted Dropbox support and we tried some things, including re-installing the Dropbox app and changing the name of my drive. Nothing worked. In the end I had to perform a deep uninstall of Dropbox using MacOS terminal to start over and get it to 'see' my drive again.

Putting aside the craziness of the fact that the only time you are able to control external drive backup is when you first plug in the drive, would anyone happen to know if there's any easier way to get Dropbox to 're-see' a drive as new if I ever have to do this again? 

While this may be helpful for Windows users, since the original poster is on a Mac (as are others), this doesn't help there. And so far, no one seems to have an answer for the Mac folks. It seems that even the Dropbox folks don't have a clue. Which sadly is about par for the course these days when it comes to support from tech companies.

I'm having the same problem. Are you seriously telling me that there's no way in the Dropbox settings to enable backup on an external drive, except to nuke all my data on the external drive and reformat it? What is going on? Dropbox want us to use this functionality for our most sensitive data? I honestly cannot believe this.

What was the hidden file you copied? Having the same issue but can't see anything obvious - even the reformat option isn't working for me.

Some option to reset the list of external drives in preferences or similar would be ideal.

It doesn't work with the hidden file. I deleted all hidden files and still no luck. I also tried to scour the local Dropbox .db files in ~/.dropbox to see if I could find the entry, but no luck either. There is no way to do this unless you delete all your data from the HD and reformat it.