source.mode "derived": union source "{label}" was refused - it derives from the grid being derived, directly or through a chain ({path}). Remove it from `from`.

Warnings reference › source.derived.union.cycle.*

Identifier

source.derived.union.cycle.*

Raised by

The grid (core)

Since

1.51.0

What happened

One parent of the union derives, directly or through a chain, from the grid doing the deriving. That entry is refused and the rest of the union works; the message prints the chain so the loop can be seen.

The fix

Remove that entry from from, or break the chain it names.

Reference

Covered in full at the API reference.