Dropbox users on GNU/Linux distributions were first surprised when an eerie notification popped up on their screen.

A thread was opened on Dropbox forums, reporting:

These days, I found my Dropbox Linux desktop client always report the following warning: "Move Dropbox location Dropbox will stop syncing in November" - clockzhong

Then came the official response:

Hi everyone, on Nov. 7, 2018, we’re ending support for Dropbox syncing to drives with certain uncommon file systems. - Jay from Dropbox

Dropbox will stop supporting all filesystems except NTFS for Windows, HFS+ or APFS for macOS and Ext4 for Linux.

But what about BTRFS or NFS, widely-used filesystems in the linux world? Even after a fresh Ubuntu install - one of the most used distributions - it is not ext4 that is installed, but BTRFS by default.

The reason invoked by Dropbox for this sudden change? "Dropbox relies on extended attributes(X-attrs) to identify files in the Dropbox folder and keep them in sync."

But Ext4 is not the only Linux filesystem that supports X-attrs: BTRFS does, as a commenter explained:

On my machine I'm running the BTRFS file system where the dropbox folder is stored - BTRFS is the standard default file system for ubuntu system partitions and supports the mentioned X-attrs attributes. On top of BTRFS there's an encryption layer running, ecryptfs, which also is Ubuntu default if home folder encryption is activated. Will the new desktop client solely run on EXT4, or will it check for if the file system where the dropbox folder is stored supports extended attributes?
eCryptfs logo with its mascot Harvey, the honey badger. eCryptfs is maintained by Canonical employees, the maker of Ubuntu.

Even worse is the fact that this surprising move on Dropbox's part could be interpreted as an attack on encryption: indeed, only unencrypted ext4 will be supported.

The 320+ comments on the forum thread show this change is causing a public backlash : this feels more as a betrayal of the GNU/Linux community than a real technical requirement

Dropbox added 2 hours ago:

If you’re running ext4 and eCryptfs and receive a notification about moving the Dropbox folder, then it’s because eCryptfs isn’t supported.

Moreover, the end of support for anything-but-ext4 could prove dramatic for enterprise Dropbox customers:

SUSE Linux has XFS as our standard /home filesystem on SUSE Linux Enterprise Server, as does Red Hat's RHEL 7, which are the two largest enterprise Linux distributions. Ubuntu with an encrypted home (standard for business use as other have pointed out) is also affected.  Enterprise customers will therefore be impacted by this move, and some of those are likely your larger customers too. - wstephenson

More than moving your folder to the only supported filesystem on Linux, or even reformatting your hard drive, this might be the time to make the switch to another cloud sync provider.

SpiderOak is an entirely valid end-to-end encrypted alternative with a Linux client (and a special unlimited backup offer for a few more hours).

While Google Drive doesn't have a Linux client, OneDrive is supported on Linux through unofficial clients. Or if you want to go the self-hosted route, you could set up your own NextCloud instance. Even the proprietary Resilio Sync supports Linux.

This is your data, the choice is yours.