“Typically, we permanently remove files and folders from our servers within 60 days of a user deleting them. However, the deleted files and folders impacted by this bug had metadata inconsistencies,” Dropbox employee Ross S said on the company’s support forum.

“So we quarantined and excluded them from the permanent deletion process until the metadata could be fixed.”

Dropbox noted that the data was only visible to the accounts of the users, and at no time did any third party have access to the exposed files.

This after users had been complaining that old files, some more than a half-decade in the past, had been showing up.

“Several different folders of old files from 2009–2011, deleted years ago but suddenly reappearing overnight,” wrote one user. “And I definitely haven’t connected to an old computer, either.”

Source: Dropbox: Oops, yeah, we didn’t actually delete all your files – this bug kept them in the cloud • The Register

Ouch, that’s pretty nasty: who knows how many other old files Dropbox (which makes money off analysing your data) has “accidentally” not deleted. Or maybe the bug was that they suddenly became visible to the user?