ERROR: parent determination failed for

[SampsonF]

For a subvol-A, readonly snapshot is created as A0 and sent over to another btrfs FS_TREE . Then, subvol-A is split into two subvols subvol-A & subvol-A/fB (mv subvol-A/fB subvol-A/fB.bak; btrfs subvol create subvol-A/fB; mv subvol-A/fB.bak/* subvol-A/fB; rm -rf subvol-A/fB.bak) To incrementally send over the changes, snapshots A10 and fB10 are created.

btrfs send -p A0 A10 | btrfs receive . # OK btrfs send -c A0 B10 | btrfs receive . # error parent determination failed

What is the correct way to send over B10 incrementally?

[luxagen]

I get this simply when trying to use a previous snapshot as a clone source without a parent, i.e. change -p to -c but leave everything else unchanged.

btrfs-progs v5.4.1