Sparsebundle corrupted via sync; no longer able to open

[dylanroscover]

For those unfamiliar, Sparsebundle is an encrypted disk image format by Apple that can grow or shrink it's file size depending on it's contents. It appears as a disk image in macOS; in reality it's a folder with many files. If any one one of these files goes missing or gets corrupted, either you can't open the image at all, or files go missing inside of it.

In my case, I created a Sparsebundle on Mac 'A' and synced via the Dropbox desktop app years ago. Recently (in January of this year), Mac 'A' had it's system restored/formatted and lost the original Sparsebundle, which was allegedly backed up to Dropbox via sync.

So, I attempted to resync the Sparsebundle back onto a new Mac, Mac 'B'. It can no longer be opened at all, whether it is downloaded from dropbox.com or synced via the Desktop app. Since this Sparsebundle is really a folder comprised of thousands of encrypted segment files (Apple calls them "bands", and they are each 8MB), I can't reasonably go back and find the single 'event' that got it corrupted; this is like searching for a needle in a haystack.

Every time a sparebundle is saved, Dropbox has to sync several hundred new files, immediately, and my best guess is it wasn't designed to handle this many events on the same timestamp, so it throws errors eventually, corrupting the master version (on dropbox.com).

The only potential solution proposed to me is the Rewind feature, however I have no idea if invoking this will result in the inability for me to rewind or fastforward through the folder again. Does anyone know if rewind can be used unlimited times to multiple restore points, for a particular file folder? Or is it a one-time-use sort of thing?

I've been asking the Dropbox support team for over two weeks now to please provide as many restores as possible (10 is ideal, but I'll take anything at this point) of the entire folder for me to test, from the most recent folder events. They have been unable to fulfill this request as of yet.

[Walter]

Hi @dylanroscover; thanks for posting on our Community and happy Monday!

I'm sorry to hear about this and I'd really like to help as much as possible. 

To directly get to the chase, you should be able to use our Rewind feature for folders in your Dropbox account as many times as you wish. 

While we're at it, note that I've also passed your comments onto your existing ticket so that we have all the relevant information under one place. I also bumped its priority so you should be hearing from our experts soon. 

I hope this helps to a certain extent Dylan. Please let me know if you have any other questions. 

[dylanroscover]

I just tried running Dropbox Rewind and received the following error:

"Couldn't rewind this folder. Try again or let us help"

[Walter]

Thanks for the follow up, Dylan.

I'm not sure if this is the case, but this error could be due to the folder's size or amount of files that the folder contains. 

In any case, I've found your existing ticket on our system and passed your comments there while also giving a bump to the ticket's priority so you should be hearing from an expert soon.

Let me know if there's anything else I can assist with in the meantime.