Dropbox sync glitch results in lost data for some subscribers

Dropbox, the popular online file storage service, acknowledged today that an issue in its Selective Sync application caused some Dropbox users to lose files they thought were safely synced to the cloud.

One user, Michael Armogan, shared the contents of an email he received from Dropbox:

We’re reaching out to let you know about a Selective Sync issue that affected a small number of Dropbox users. Unfortunately, some of your files were deleted when the Dropbox desktop application was shut down or restarted while you were applying Selective Sync settings.

Our team worked hard to restore files that were deleted from your account. You can see which of your files were affected and whether or not we’ve been able to restore them on this personalized web page.

We’re very sorry about what happened. There’s nothing more important to use than making sure your information is safe and always available. Our team has fixed the issue and put additional tests in place to prevent this from happening in the future.

As compensation, Dropbox said it was offering affected users a free one-year Dropbox Pro subscription.

So far, Dropbox has not acknowledged the issue on its blog, via its Twitter account, or on its Facebook page.

This isn’t the first time Dropbox has had issues with the security or reliability of its service. In 2011, Dropbox admitted that it had inadvertently published code on its web site that allowed anyone to sign in to any Dropbox account without credentials.

And in 2012 the company revealed that “usernames and passwords recently stolen from other websites were used to sign in to a small number of Dropbox accounts.” A letter from the Dropbox CTO to affected users acknowledged that accounts had been “compromised by a third party [and] data was downloaded from your Dropbox account.”

A cloud-based storage service runs on trust. Files stored in the cloud have to be secure from outside intruders and available when needed. A sync failure of this sort is especially insidious because there’s no way to know that some files have unexpectedly vanished both from the cloud and from devices where they had previously been synced.

In both of those incidents, as in today’s disclosure, Dropbox apologized and said it was taking steps to improve the safety and reliability of the service.

Aggressive competition from Apple, Google, and Microsoft has driven down cloud storage pricing in the past year. That led Box, a competitor to Dropbox, to delay its IPO. Dropbox has managed to remain independent but the economics of its business are being seriously challenged as their product turns into a feature, available for free (or nearly so) to anyone who buys an Apple device, a Microsoft Office subscription, or a Google Apps account.

Update: 13-Oct 6:50PM A spokesperson confirms that the email reprinted above is legitimate and that Dropbox sent identical email messages to all persons affected by this issue. The spokesperson provided this statement:

"We've fixed the Selective Sync issue that affected a small number of users and reached out to them to help restore their files. Issues like this aren't acceptable at Dropbox, and we've implemented additional testing to prevent this from happening again."

See also:

• Can Dropbox and Box survive as independent services?
• Dropbox gets hacked ... again
• Sorry, Dropbox, I still don't trust you
• Google clones Dropbox: lock, stock, and privacy gaffe
• Eight business-class alternatives to Dropbox
• Make your cloud safer: How to enable two-factor authentication for the most popular cloud services