Dropbox Smart Sync uses lightweight integrations with the Windows and macOS operating systems to function. These integrations are called minifilter drivers (on Windows) and system extensions (on macOS), and they allow Dropbox to automatically download your files as soon as you open them.
These integrations work much like the drivers you install to use a printer, copier, or external mouse. In this case, these integrations allow the Dropbox Smart Sync feature to work. You won’t see either the system extension or driver unless you use Dropbox Smart Sync.
On macOS 10.13 (High Sierra), you may see a System Extension Blocked prompt when trying to run the Dropbox desktop application for the first time. If you don’t allow access for the system extension, you won’t be able to use Smart Sync.
To enable the Dropbox system extension, simply follow the steps that appear on your computer as you’re setting up Dropbox:
If you don’t allow access for the system extension or driver, you won't be able to use Dropbox Smart Sync. However, the main Dropbox desktop application will still work like normal.
If you unintentionally exited out of this process, you can easily allow Dropbox access:
Use of a system extension or driver is common among many popular systems:
Dropbox used publicly-available APIs from Apple and Microsoft to write the system extension and driver. No additional admin permissions are required (beyond what Dropbox has always needed to function).
System extensions enable "callbacks." Callbacks are real-time calls that confirm you have permission to do things like move, delete, or change ownership of files in shared spaces (like a folder). If you don’t have these file access permissions, system extensions allow Dropbox to send warnings when you may be taking an action that could unshare folders or delete shared content.
System extensions and drivers can give applications additional access to your computer’s operating system. Dropbox is cautious in only using these extensions to improve your experience with our app.
Some notes on what we don’t do:
Dropbox takes great measures to protect your data and privacy, and we designed the system extension and driver with security and stability as top priorities. In fact, many of the engineers who wrote this extension previously worked on filesystem technologies at various OS vendors.
These components have gone through extensive security reviews with internal security teams, as well as audits done by external penetration testers. We’ve run these components both internally at Dropbox and in cooperation with enterprise-scale beta customers. In both cases these components ran successfully.
These integrations are core to current and future Dropbox client services. There is no way to disable or opt-out of using the system extension or minifilter driver on the Dropbox desktop client. Doing so would also disable important alerts that prevent users from accidentally deleting shared data, or taking unintended file actions.
If you don’t want to install the Dropbox desktop application, you can view, share, and download your files without the desktop integration by using only the Dropbox website at dropbox.com.
Please note that your privacy and security are of the utmost importance to us. Smart Sync and this component have been subjected to rigorous testing and inspection to ensure stability and security.
Smart Sync is an opt-in feature so you can choose to opt-out if you wish to do so. However, you cannot use Smart Sync without enabling the system extension or driver.