After a lot of additional testing and a number of small fixes and improvements to the database code, we have now started rolling out LXD 3.15 to users of the stable channel.
Note that it is generally not possible to rollback to LXD 3.14, so avoid using snap rollback, instead, should something go wrong, first attempt to restart LXD with systemctl reload snap.lxd.daemon. If that doesn’t help, please file a bug at https://github.com/lxc/lxd/issues where we can quickly diagnose any issue and provide a hotfix or targeted instructions if needed.
So far the only issues we’ve noticed have been related to specific kernel versions combined with less usual filesystems and direct I/O support.
Specifically, the two issues that have been identified and resolved were LXD on ZFS 0.8 with Linux 5.2 (partial direct I/O support) and LXD on shiftfs (direct I/O detection issue).