The 2018 Linux ext4-only restriction broke sync for many users

In August 2018 Dropbox quietly warned Linux users, via a desktop notification, that beginning 7 November 2018 its client would sync only on the ext4 filesystem. On the announced date, Linux installations using any other filesystem — including XFS, ZFS, ext2, ext3, Btrfs, and ext4 volumes layered with encryption such as LUKS or eCryptfs — stopped syncing entirely.

Dropbox justified the change by saying it relies on extended attributes (xattrs) to identify files in the Dropbox folder and keep them in sync, and that it would support only the 'most common' filesystems with xattrs support to ensure stability and a consistent experience. Critics pointed out the explanation did not hold up technically: several of the dropped filesystems, notably XFS (the default on Red Hat Enterprise Linux), fully support extended attributes. The restriction also penalized security-conscious users who kept their Dropbox data on encrypted volumes, forcing them to choose between disk encryption and a working sync client.

While this was a policy/engineering decision rather than a bug, the practical effect for affected users was the same as a reliability failure: data that had been syncing reliably for years suddenly stopped being mirrored or available through Dropbox, with reformatting to a supported, unencrypted ext4 volume offered as the only sanctioned remedy.